This README file was generated on 2023-12-19 by Cristo O. Romano.

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GENERAL INFORMATION

1. Title of Dataset: Data from ‘Redefining the Huayquerian Stage (Upper Miocene to Lower Pliocene) of the South American chronostratigraphic scale based on biostratigraphical analyses and geochronological dating’

2. Author Information

A. Corresponding Author Contact Information

Name: Cristo O. Romano

Institution: Instituto Argnetino de Nivología, Glaciología y Ciencias Ambientales (IANIGLA) / Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)

Address: Mendoza, Mendoza Province, Argentina

Email: romano.cristo@gmail.com

B. Co-authors Information

Name: Alberto C. Garrido

Institution: Museo Provincial de Ciencias Naturles Prof. Dr Juan Olsacher (MOZ) / Centro de Investigación en Geociencias de la Patagonia (CIGPat)

Address: Zapala, Neuquén Province, Argentina

Name: David L. Barbeau Jr

Institution: School of the Earth, Ocean & Environment, University of South Carolina

Address: Columbia, South Carolina, USA

Name: Rocío B. Vera

Institution: Instituo de Estudios Andinos 'Don Pablo Groeber' (IDEAN), Estudios Paleobiológicos en Ambientes Contienteales, Universidad de Buenos Aires (UBA) / Facultad de Ciencias Exactas y Naturales, Departamento de Ciencis Geológicas, Laboratoio de Paleontología de Vertebrados (UBA) / CONICET

Address: Ciudad Autónoma de Buenos Aires, Argentina

Name: Ricardo Bonini

Institution: Instituto de Investigacioñnes Arqueológicas y Paleontológicas del Cuaternario Pampeano (INCUAPA), Faculta de Ciencias Sociales, Universidad Nacional del Centro de la Provincia de Buenos Aires / CONICET

Address: Olavarría, Buenos Aires Province, Argentina

Name: Alberto Boscaini

Institution: Instituto de Ecología, Genética y Evolución de Buenos Aires (IEGEBA), Departamento de Ecología, Genética y Evolución, Faculta de Ciencias Exactas y Naturales, UBA / CONICET

Address: Ciudad Autónoma de Buenos Aires, Argentina

Name: Esperanza Cerdeño

Institution: IANIGLA / CONICET

Address: Mendoza, Mendoza Province, Argentina

Name: Laura E. Cruz

Institution: División Paleontología Vertebrados, Museo Argentino de Ciencias Naturales Bernardino rivadavia (MACN) / Laboratroio de Anatomía y Biología Evolutiva de los Vertebrados (LABEV-UNLu), Departamento de Ciencias Básicas, Universidad Nacional de Luján (UNLu) / CONICET

Address: Ciudad Autónoma de Buenos Aires, Argentina

Name: Graciela I. Esteban

Institution: Instituto Superior de Correlación Geológica (INSUGEO), Facultad de Ciencias Naturales e Instituto Miguel Lillo, Universidad Nacional de Tucumán

Address: San Miguel de Tucumán, Tucumán Province, Argentina

Name: Marcelo S. de la Fuente

Institution: Instituto de Evolución, Ecología Histórica y Ambiente (IDEVEA) / CONICET

Address: San Rafael, Mendoza Province, Argentina

Name: Marcos Fernández-Monescillo

Institution: Cátedra y Museo de Paelontología, Faculta de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de Córdoba / CONICET

Address: Córdoba, Córdoba Province, Argentina

Name: Juan C. Fernicola

Institution: División Paleontología Vertebrados, MACN / LABEV-UNLu / CONICET

Address: Ciudad Autónoma de Buenos Aires, Argentina

Name: Verónica Krapovickas

Institution: IDEAN / UBA / CONICET

Address: Ciudad Autónoma de Buenos Aires, Argentina

Name: M. Carolina Madozzo-Jaén

Institution: INSUGEO / CONICET

Address: San Miguel de Tucumán, Tucumán Province, Argentina

Name: M. Encarnación Pérez

Institution: Museo Paleontológico Egidio Feruglio (MEF) / CONICET

Address: Trelew, Chubut Province, Argentina

Name: François Pujos

Institution: IANIGLA / CONICET

Address: Mendoza, Mendoza Province, Argentina

Name: Luciano Rasia

Institution: División Paleontología Vertebrados, Museo de La Plata, Universidad Nacional de La Plata / CONICET

Address: La Plata, Buenos Aires Province, Argentina

Name: Guillermo Fm. Turazzini

Institution: Laboratorio de Morfología Evolutiva y Paleobiología de Vertebrados, Departamento de Biodiversidad y Biología Experimental, Faculta de Ciencias Exactas y Naturales, Universidad de Buenos Aires (UBA) / CONICET

Address: Ciudad Autónoma de Buenos Aires, Argentina

Name: Bárbara Vera

Institution: Centro de Investigación Esquel de Montaña y Estepa Patagónica (CIEMEP) / CONICET

Address: Esquel, Chubut Province, Argentina

Name: Ross D. E. MacPhee

Institution: Department of Mammalogy, American Museum of Natural History

Address: New York, NY, USA

Name: Analía M. Forasiepi

Institution: IANIGLA / CONICET

Address: Mendoza, Mendoza Province, Argentina

Name: Francisco J. Prevosti

Institution: Museo de Ciencias Antropológicas y Naturales, Universidad Nacional de La Rioja (UNLaR) / CONICET

Address: La Rioja, La Rioja Province, Argentina

3. Date of data colection (time range): 2013-2019

4. Geographic location of data colecction: Las Huayquerías del Este, San Carlos department, Mendoza Province, Argentina.

5. Information about funding sources that supported the collection of the data: This research was supported by ANPCYT (Projects PICT 2015-966, 2019-2874), Argentina

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SHARING/ACCESS INFORMATION

6. Licenses/restrictions placed on the data: CC0 1.0 Universal (CC0 1.0) Public Domain

7. Links to publications that cite or use the data:

Romano, C. O., Garrido, A. C., Barbeau, D. L., Vera, R. B., Bonini, R., Boscaini, A., Cerdeño, E., Cruz L. E., Esteban, G. I., de la Fuente, M. S., Fernández-Monescillo, M., Fernicola, J. C., Krapovickas, V., Madozzo-Jaén, M. C., Pérez, M. E., Pujos, F., Rasia, L., Turazzini, G. F., Vera, B., MacPhee, R. D. E., Forasiepi, A. M. & Prevosti, F. J. (in press). Redefining the Huayquerian Stage (Upper Miocene – Lower Pliocene) of the South American chronostratigraphic scale based on biostratigraphical analyses and geochronological dating. Papers in Palaeontology, DOI: 10.1002/spp2.1539

8. Links to other publicly accessible locations of the data: None

9. Links/relationships to ancillary data sets: None

10. Was data derived from another source? No

A. If yes, list source(s): NA

11. Recommended citation for this dataset:

Romano, C. O., Garrido, A. C., Barbeau, D. L., Vera, R. B., Bonini, R., Boscaini, A., Cerdeño, E., Cruz L. E., Esteban, G. I., de la Fuente, M. S., Fernández-Monescillo, M., Fernicola, J. C., Krapovickas, V., Madozzo-Jaén, M. C., Pérez, M. E., Pujos, F., Rasia, L., Turazzini, G. F., Vera, B., MacPhee, R. D. E., Forasiepi, A. M. & Prevosti, F. J. (in press). Data from: 'Redefining the Huayquerian Stage (Upper Miocene – Lower Pliocene) of the South American chronostratigraphic scale based on biostratigraphical analyses and geochronological dating.' Dryad Digital Repository, https://doi.org/10.5061/dryad.ngf1vhj0t

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DATA & FILE OVERVIEW

12. File List (description of the data and file structure)

A- Data 1. Excel file with raw U-Pb zircon geochronology data of tuffaceous samples (except T3), from Huayquerías del Este, Mendoza Province, Argentina.

B- Data 2. Excel file with raw U-Pb zircon geochronology data of T3 tuff sample, from Huayquerías del Este, Mendoza Province, Argentina. Including information about the methodology (provided by the laboratory).

C- Data 3. Excel file with detailed information on the fossil specimens collected in the Huayquerías del Este, Argentina.

D- Data 4. Excel file with presence-absence matrices for similarity analysis.

[Access this dataset on Dryad] https://doi.org/10.5061/dryad.ngf1vhj0t

13. Relationship between files, if important: The presence and absence matrices in Data 4 are based on the specimens listed in Data 3.

14. Additional related data collected that was not included in the current data package: None

15. Are there multiple versions of the dataset? No
A. If yes, name of file(s) that was updated: NA

i. Why was the file updated? NA

ii. When was the file updated? NA

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DATA-SPECIFIC INFORMATION FOR: 'Data 1.csv'

1. Samples: Around 3 kg of rock from each of the 10 tuffaceous levels (T): T1, T2, T4, T5, T6, T10, T11, TM1, and TM2.

2. Geographic location of data colecction: Las Huayquerías del Este, San Carlos department, Mendoza Province, Argentina.

3. Formation, fossil site and coordinates (latitude; longitude) of the collected samples:

T0: Huayquerías Formation, Río Seco de la Horqueta, 33°50'00.4"S, 68°28'59.6"W

T1: Bajada Grande Formation, Río Seco de la Isla Grande, 33°58'50.6"S, 68°26'31.6"W

T4: Bajada Grande Formation, Río Seco de la Isla Grande, 33°58'43.4"S, 68°26'15.8"W

T5: Bajada Grande Formation, Cerro Parvitas, 33°44'30.2"S, 68°40'55.8"W

T6: Huayquerías Formation, Río Seco de la Última Aguada, 33°54'23.8"S, 68°27'18.4"W

T10: Huayquerías Formation, Río Seco de Los Pajaritos, 33°55'28.5"S, 68°26'51.0"W

T11: Tunuyán Formation, Río Seco de Los Pajaritos, 33°44'30.2"S, 68°40'55.8"W

TM1: Huayquerías Formation, Río Seco del Carrizalito, 33°54'58.1"S, 68°32'55.0"W

TM2: Huayquerías Formation, Río Seco del Carrizalito, 33°54'53.9”S, 68°33'02.1"W

4. Number of variables: 23

5. Tipe of case: spots on zircon crystals through laser ablation

6. Number of cases/rows by sample (T):

T0: 69

T1: 36

T4: 33

T5: 22

T6: 26

T10: 39 (big crystals) and 24 (small crystals)

T11: 51

TM1: 38

TM2: 22

7. Variable List:

* analysis: spot on zircon crystal identifier

* 207Pb/235U [ISOTOPIC RATIOS]: The relative abundance of 207Pb with respect to 235U measured in the zircon crystal.

* prop. 2s no sys (%) [ISOTOPIC RATIOS]: The 2s uncertainty of the measured 207Pb / 235U ratio in the zircon crystal expressed as a percent, including analytical uncertainties and propagated uncertainties but not including systematic uncertainties. Analytical uncertainties capture the natural variability within the zircon. Propagated uncertainties incorporate uncertainty related to in-run analytical age uncertainty of the primary reference material, and the correction of down-hole fractionation and instrument drift during data reduction

* prop. 2s w sys (%) [ISOTOPIC RATIOS]: The 2s uncertainty of the measured 207Pb / 235U ratio in the zircon crystal expressed as a percent, including analytical uncertainties, propagated uncertainties, and systematic uncertainties. Analytical uncertainties capture the natural variability within the zircon. Propagated uncertainties incorporate uncertainty related to in-run analytical age uncertainty of the primary reference material, and the correction of down-hole fractionation and instrument drift during data reduction. Systematic uncertainties include excess variance determined from long-term analysis of a monitor reference material, decay constant uncertainties, and primary reference material age uncertainties

* 206b/238Pb [ISOTOPIC RATIOS]: The relative abundance of 206Pb with respect to 238U measured in the zircon crystal

* prop. 2s no sys (%) [ISOTOPIC RATIOS]: The 2s uncertainty of the measured 206Pb / 238U ratio in the zircon crystal expressed as a percent, including analytical uncertainties and propagated uncertainties but not including systematic uncertainties. Analytical uncertainties capture the natural variability within the zircon. Propagated uncertainties incorporate uncertainty related to in-run analytical age uncertainty of the primary reference material, and the correction of down-hole fractionation and instrument drift during data reduction

* prop. 2s w sys (%) [ISOTOPIC RATIOS]: The 2s uncertainty of the measured 206Pb / 238U ratio in the zircon crystal expressed as a percent, including analytical uncertainties, propagated uncertainties, and systematic uncertainties. Analytical uncertainties capture the natural variability within the zircon. Propagated uncertainties incorporate uncertainty related to in-run analytical age uncertainty of the primary reference material, and the correction of down-hole fractionation and instrument drift during data reduction. Systematic uncertainties include excess variance determined from long-term analysis of a monitor reference material, decay constant uncertainties, and primary reference material age uncertainties

* 206/238 vs 207/235 error correlation [ISOTOPIC RATIOS]: A measurement of the covariance between the measured 206Pb/238U and 207Pb/235U ratios

* 238U/206Pb [ISOTOPIC RATIOS]: The relative abundance of 238U with respect to 206Pb measured in the zircon crystal

* prop. 2s no sys (%) [ISOTOPIC RATIOS]: The 2s uncertainty of the measured 238U / 206Pb ratio in the zircon crystal expressed as a percent, including analytical uncertainties and propagated uncertainties but not including systematic uncertainties. Analytical uncertainties capture the natural variability within the zircon. Propagated uncertainties incorporate uncertainty related to in-run analytical age uncertainty of the primary reference material, and the correction of down-hole fractionation and instrument drift during data reduction

* prop. 2s w sys (%) [ISOTOPIC RATIOS]: The 2s uncertainty of the measured 238U / 206Pb ratio in the zircon crystal expressed as a percent, including analytical uncertainties, propagated uncertainties, and systematic uncertainties. Analytical uncertainties capture the natural variability within the zircon. Propagated uncertainties incorporate uncertainty related to in-run analytical age uncertainty of the primary reference material, and the correction of down-hole fractionation and instrument drift during data reduction. Systematic uncertainties include excess variance determined from long-term analysis of a monitor reference material, decay constant uncertainties, and primary reference material age uncertainties

* 207Pb/206Pb [ISOTOPIC RATIOS]: The relative abundance of 207Pb with respect to 206Pb measured in the zircon crystal

* prop. 2s no sys (%) [ISOTOPIC RATIOS]: The 2s uncertainty of the measured 207Pb / 206Pb ratio in the zircon crystal expressed as a percent, including analytical uncertainties and propagated uncertainties but not including systematic uncertainties. Analytical uncertainties capture the natural variability within the zircon. Propagated uncertainties incorporate uncertainty related to in-run analytical age uncertainty of the primary reference material, and the correction of down-hole fractionation and instrument drift during data reduction

* prop. 2s w sys (%) [ISOTOPIC RATIOS]: The 2s uncertainty of the measured 207Pb / 235Pb ratio in the zircon crystal expressed as a percent, including analytical uncertainties, propagated uncertainties, and systematic uncertainties. Analytical uncertainties capture the natural variability within the zircon. Propagated uncertainties incorporate uncertainty related to in-run analytical age uncertainty of the primary reference material, and the correction of down-hole fractionation and instrument drift during data reduction. Systematic uncertainties include excess variance determined from long-term analysis of a monitor reference material, decay constant uncertainties, and primary reference material age uncertainties

* 238/206 vs 207/206 error correlation [ISOTOPIC RATIOS]: A measurement of the covariance between the measured 238U / 206Pb and 207Pb / 206Pb ratios

* U [ELEMENTAL CONCENTRATIONS]: The concentration of uranium measured in the zircon crystal

* U/Th [ELEMENTAL CONCENTRATIONS]: The relative concentrations of uranium with respect to Th measured in the zircon crystal

* 207Pb/235U age (Ma) [APPARENT AGES]: The apparent age of the zircon crystal in millions of years ago (Ma) when calculated from the 207Pb / 235U ratio measured from the zircon crystal

* prop. 2s w sys (Myr) [APPARENT AGES]: The apparent age of the zircon crystal in millions of years ago (Ma) when calculated from the 207Pb / 235U ratio measured from the zircon crystal

* 206Pb/238U age (Ma) [APPARENT AGES]: The apparent age of the zircon crystal in millions of years ago (Ma) when calculated from the 206Pb / 238U ratio measured from the zircon crystal. For crystals younger than ca. 1000 Ma, this apparent age is the most reliable

* prop. 2s w sys (Myr) [APPARENT AGES]: The 2s uncertainty of the age calculated from the measured 206Pb / 238U ratio in the zircon crystal expressed in millions of years (Myr), including analytical uncertainties, propagated uncertainties, and systematic uncertainties. Analytical uncertainties capture the natural variability within the zircon. Propagated uncertainties incorporate uncertainty related to in-run analytical age uncertainty of the primary reference material, and the correction of down-hole fractionation and instrument drift during data reduction. Systematic uncertainties include excess variance determined from long-term analysis of a monitor reference material, decay constant uncertainties, and primary reference material age uncertainties

* 207Pb/206Pb age (Ma) [APPARENT AGES]: The apparent age of the zircon crystal in millions of years ago (Ma) when calculated from the 207Pb / 206Pb ratio measured from the zircon crystal. For crystals older than ca. 1000 Ma, this apparent age is the most reliable

* prop. 2s w sys (Myr) [APPARENT AGES]: The 2s uncertainty of the age calculated from the measured 207Pb / 206Pb ratio in the zircon crystal expressed in millions of years (Myr), including analytical uncertainties, propagated uncertainties, and systematic uncertainties. Analytical uncertainties capture the natural variability within the zircon. Propagated uncertainties incorporate uncertainty related to in-run analytical age uncertainty of the primary reference material, and the correction of down-hole fractionation and instrument drift during data reduction. Systematic uncertainties include excess variance determined from long-term analysis of a monitor reference material, decay constant uncertainties, and primary reference material age uncertainties

* conc. (%) [APPARENT AGES]: The degree of concordance between apparent ages calculated from the 206Pb / 238U ratio relative to those calculated from the 207Pb / 206Pb ratio, expressed as a percentage of the former divided by the latter. Concordance cannot be reliably determined for young crystals (i.e., <500-800 Ma) because of the low concentration of 207Pb in young crystals

8. Missing data codes: None

9. Specialized formats or other abbreviations used: None

10. Methodology for data acquisition:

Zircon geochronology

We sampled nine tuffaceous levels for dating (T), collecting c. 3 kg of rock, across the Huayquerías, Tunuyán, and Bajada Grande formations. The tuff levels were georeferenced using Global Positioning System (GPS).

Zircon aliquots were acquired through conventional density and magnetic separation procedures conducted in the School of the Earth, Ocean and Environment at the University of South Carolina (USA). U-Pb zircon geochronology was achieved by laser-ablation inductively coupled plasma mass-spectrometry (LA-ICP-MS) at the University of South Carolina’s Center for Elemental Mass Spectrometry. Sample preparation, analysis, reduction, and filtering methods are detailed in Appendix S1 (1.1. Zircon geochronology) from Romano et al. (2023).

Sample preparation methods

Crystals were picked and mounted and then imaged using cathodoluminescence scanning electron microscopy at the Southeastern North Carolina Regional Microanalytical and Imaging Consortium at Fayetteville State University (USA).

U-Pb zircon geochronology was achieved by laser-ablation inductively coupled plasma mass-spectrometry (LA-ICP-MS) at the University of South Carolina’s Center for Elemental Mass Spectrometry using a high-resolution single-collector Thermo (now Thermo Fisher) Element2 mass-spectrometer attached to a PhotonMachines (now Teledyne) G2 Analyte 193 nm ArF exciplex laser using a 25 µm circular spot. For each aliquot, sample (aka ‘unknown’) zircons were analyzed in batches of four to five analyses each, separated by the analysis of two natural reference zircons of known and well-constrained U-Pb isotope-dilution thermal ionization mass-spectrometry (ID-TIMS) ages. In order to maximize the age data acquired from each sample, in some cases sufficiently large sample crystals were ablated by multiple laser spots. Indurated samples were progressively disaggregated to sub-500 µm particle sizes using a Bico Braun WD Chipmunk jaw crusher and Bico Braun UA Pulverizer disc mill. Particularly friable samples were disaggregated by gentle treatment in a large mortar and pestle. At the end of each crushing or milling step, all material finer than 500 µm was removed from further disaggregation via separation with a US-35 mesh stainless steel sieve. Resulting disaggregated grains were separated by hydrodynamic characteristics (mainly density) using a MD Mineral Technologies MK-2 Gemeni shaking water table, operating at approximately 6 liters/minute water flow and 6 Hz shaking. Grain splits entering the most distant three of seven receptacles (those containing the densest grains) were combined and proceeded to further processing (below); splits entering the upper four receptacles were examined to confirm the absence of zircon, and archived.

The aforementioned dense grains were further separated by their hydrodynamic characteristics using a 25 cm diameter ABS plastic Garrett-type gold pan with tap water, and a portable wash basin to retain the discarded grains. Grains retained within the gold pan proceeded to further processing; splits exiting the gold pan were examined to confirm the absence of zircon, and archived.

Retained grains were then progressively separated by their effective magnetic susceptibility first with a hand-magnet, and then with an L-1 Frantz isodynamic magnetic separator operating at left-right and front-back angles of 15° and 20°, respectively. Paramagnetic grain fractions were progressively removed in ~0.2 ampere increments up to ~1.0 amperes, and archived. Nonmagnetic fractions at ~1.0 amperes proceeded to further processing.

Resulting nonmagnetic dense mineral fractions were combined with lithium metatungstate (~2.89 g/cm3) in 15 mL centrifuge tubes, agitated and left to settle for at least four hours until grains separated into fully floating and sunken fractions with an intervening clear heavy liquid window. Centrifuge tubes were then placed vertically into liquid nitrogen to a sufficient depth to submerge one-half of the heavy liquid window. Upon complete freezing of the submerged liquid and sunken fraction, the remaining liquid and floating fraction were poured off into a funnel lined with a 20 µm pore-diameter filter paper cone (Fisherbrand Grade P8), rinsed repeatedly with de-ionized water, transferred to a second filter paper, re-rinsed, dried, and archived. The frozen sunken separate and remaining liquid were thawed in a 30°C oven, and poured off into a separate funnel lined with a 20 µm pore-diameter filter paper cone, and rinsed repeatedly with de-ionized water, transferred to a second filter paper, re-rinsed,and then dried in a ~30°C oven.

Zircon crystals were picked from the resulting high-density nonmagnetic grains and placed onto double-sided tape attached to a 6” square glossy ceramic tile, and within the bounds of a 1” Buehler circular ring form, cut to ~1 cm depth. These grains were then bound in place using Buehler Epo-Thin epoxy resin, poured to a depth of approximately 5 mm within the ring form. Upon at least 48 hours of curing, the resulting mounts were pried from their tiles, and gently ground using wet sandpaper of 600 grit as needed in order to expose the grain cores, followed by polishing using 1 µm Buehler Micropolish Alumina polishing powder suspended in de-ionized water deployed upon Buehler TexMet C polishing cloths, and a Buehler MINIMET 1000 auto-polisher operating at 20-40 cycles per minute and 2–4 pounds of downward force. Such procedures were repeated in 5–20 minute increments until a reflected light microscope revealed an absence of scratches in target zircons. Mounts were then sonicated in a de-ionized water bath for ~15 minutes and then dried in a 30°C oven. Mounts were imaged using cathodoluminence scanning electron microscopy with a JEOL JXA-8530F Hyperprobe Electron Probe Microanalyzer.

Analytical methods

In this work, we used natural zircon 91500 (1062.4 ± 1.9 Ma 206Pb/238U ID-TIMS age, [U]= 43–114 ppm: Wiedenbeck et al. 1995, 2004) as our primary reference material (‘standard’) for all analyses. We used either Fish Canyon Tuff (28.61 ± 0.08 Ma 206Pb/238U CA-ID-TIMS age, [U]= 209–459 ppm: Bachmann et al. 2007) or SL2 (563.5 ± 3.2 Ma 206Pb/238U ID-TIMS age, [U]= ~518 ppm: Gehrels et al. 2008) as our secondary reference material to monitor the accuracy and precision of correction using the 91500 reference material. In most samples, we analyzed either Plešovice (337.1 ± 0.2 Ma 206Pb/238U ID-TIMS age, [U]= ~755 ppm: Sláma et al. 2008; Horstwood et al. 2016) or 94–35 (55.5 ± 1.5 Ma 206Pb/238U ID-TIMS age, [U]= 64–228 ppm: Klepeis et al. 1998) as an additional monitor ‘standard’ after every ~fourteenth ‘unknown’ analysis in order to further assess the quality of standard-unknown bracketing corrections.

Analysis involved grain-ablation with a PhotonMachines/Teledyne Analyte G2 193 nm (deep ultraviolet) ArF exciplex laser with a (circular) spot diameter of 25 µm, aimed at the centers of the individual sample (‘unknown’) and reference (aka ‘standard’) zircon grains, mounted in 1” polished epoxy resin pucks contained within a nine-hole stage nested within a two-volume HelEx sample cell. For each aliquot, unknown zircons were analyzed in 4 to 15 batches (depending on the sample) of four to five grains each, separated by the analysis of two natural reference zircons of known and well-constrained U-Pb isotope-dilution thermal ionization mass-spectrometry (ID-TIMS) ages. For most samples, a third reference material was analyzed as a known monitor ‘standard’ after every ~fourteenth ‘unknown’ analysis in order to compare the quality of standard-unknown bracketing corrections for each of the two used reference materials.

This standard-unknown bracketing approach is required to correct for instrumental age-offset and drift, and down-hole inter-elemental fractionation, carrying with it modest uncertainties in age accuracy and precision that are sacrificed for the efficiency of collecting large datasets. In this study, reference material 91500 (1065.4 ± 0.3 Ma 207Pb/206Pb ID-TIMS weighted-mean age: Wiedenbeck et al. 1995; [U]= 43–114 ppm: Wiedenbeck et al. 2004) was analyzed after every four to five ‘unknown’ analyses. Reference material Fish Canyon (28.48 ± 0.02 Ma 206Pb/238U ID-TIMS weighted-mean age; [U]= 200–850 ppm: Schmitz & Bowring 2001) or SL2 (563.5 ± 3.2 Ma 206Pb/238U ID-TIMS weighted-mean age; [U]= ~518 ppm: Gehrels et al. 2008) was analyzed after every 91500 analyses. Reference material Plešovice (337.1 ± 2.0 Ma 206Pb/238U ID-TIMS weighted-mean age (Sláma et al. 2008; Horstwood et al. 2016), [U]= 465–1106 ppm: Sláma et al. 2008) or 94–35 (55.5 ± 1.5 Ma 206Pb/238U ID-TIMS weighted-mean age, [U]= 64–228 ppm: Klepeis et al. 1998) was analyzed after every third set of four to five unknowns of each aliquot for most samples, and used to assess and compare the accuracy of corrections based on the 91500, Fish Canyon and SL2 reference materials.

Prior to analytical sessions, the coupled LA-HR-SC-ICP-MS system was manually tuned to optimize performance using 5 µm/s line scans of large fragments of the SL2 natural zircon reference material, with the laser otherwise set to parameters identical to the analytical session (see below). The tuning optimization routine involved adjusting torch position, then sample and HelEx gas flows to maximize signal (monitored by 238U cps) while minimizing oxide formation (monitored by UO/U) and inter-elemental fractionation (monitored by 232Th/238U). Optimized signal intensities were approximately 2x106 cps for 238U from SL2. UO/U values were ~0.3%, Th/U values were ~0.1 (very close to the accepted SL2 value of 0.13: Gehrels et al. 2008).

During each analysis, the ablated material was transported in He carrier gas flowing at ~0.4 and ~0.1 liters/minute (LPM), respectively, from internal (MFC1) and external (MFC2) HelEx sample cell mass flow controllers downstream to the mass-spectrometer, where it was mixed with ~1 LPM of Ar sample gas in a PhotonMachines mixing bulb, and injected into the dry plasma source of a Thermo ELEMENT2 high-resolution single-collector mass-spectrometer, where the ablatant was ionized, passed through sample and skimmer cones, and then discriminated using the ELEMENT2’s double-focusing magnetic sector field mass analyzer.

Samples T0, TM1, TM2, and T6: Analysis of each unknown and reference zircons involved the collection of 6 s of background data acquisition without the laser firing, followed by laser ablation of targeted zircons for 30 s at a laser repetition rate of 10–11 Hz and laser fluence of approximately 11 J/cm2, followed by at least 20 s for signal washout, baseline (blank) stabilization, and data compilation and recording. Signal intensity data were collected for masses 202, 204, 206, 207, 208, 232, and 238 using the ion counting mode of the ELEMENT2’s secondary electron multiplier (SEM) detector. Analysis of masses 206, 207, 208, 232, and 238 would switch automatically to analog mode above approximately 5 million cps. Mass 235 was determined by dividing the signal intensity of mass 238 by 137.818 (Horstwood et al. 2016).

All samples except T0, TM1, TM2, and T6: Following the analyses of the first four tuff samples, our laboratory adjusted its protocol to optimize data collection, having discovered that data resolution does not significantly improve beyond ~12 s of grain ablation at ~10 Hz. Therefore, for all samples other than those aforementioned, we reduced ablation times to 16 s for all analyses. However, in order to increase the 206Pb counts required for an accurate 206Pb/238U age determined from young (i.e. low-daughter) grains, we employed a modified method that skipped data collection on 208Pb, and reduced dwell times on 207Pb and 232Th. We also employed a pre-ablation routine to remove any surface contamination introduced during the mounting, grinding and polishing procedures, or during storage and handling, and to ensure a horizontal exposed surface prior to ablation.

Immediately prior to each analysis of unknown or reference zircon, 7 shots of a 50 µm circular laser spot were fired at a rate of 11 Hz at a position concentric with the (25 µm) ablation target, followed by 10 s delay for material to wash out and signal baselines to stabilize. Subsequent analysis of unknown and reference zircons involved the collection of 6 s of background data acquisition without the laser firing, followed by laser ablation of targeted zircons for 16 s at a laser repetition rate of 10–11 Hz and laser fluence of approximately 11 J/cm2, followed by at least 20 s for signal washout, baseline (blank) stabilization, and data compilation and recording. Signal intensity data were collected for masses 202, 204, 206, 207, 232, and 238 using the ion counting mode of the ELEMENT2’s secondary electron multiplier (SEM) detector. Analysis of masses 206, 207, 232, and 238 switched automatically to analog mode above approximately 2x106 cps. Mass 235 was determined by dividing the signal intensity of mass 238 by 137.818 (Horstwood et al. 2016).

Data reduction methods

Resulting data were reduced using the UPbGeochronology3 data reduction scheme of the Iolite (v. 2.4) software package (Paton et al. 2010) in the WaveMetrics IgorPro software environment. This approach subtracts background (‘blank’) signals, models and corrects inter-element downhole fractionation and instrument age-offsets and drift, and calculates individual analyses’ apparent ages, propagated uncertainties, and error correlations. We used an in-house data assessment table to exclude excessively discordant or uncertain ages. All volcanogenic and xenocrystic or detrital zircons with ages younger than 500 Ma had insufficient total counts of 207Pb to generate reliable 207Pb/206Pb ages for concordance calculations and filtering, so all grains with 206Pb/238U ages younger than 500 Ma were included without concordance filtering. Xenocrystic zircons with ages greater than 500 Ma that were less than 70% concordant (i.e. grains with 206Pb/238U ages younger than 70% of their 207Pb/206Pb ages) or more than 5% - 10% reverse discordant (i.e. grains with 206Pb/238U ages older than 105% of their 207Pb/206Pb ages were excluded from consideration as a result of likely disruption to an ideally closed U-Pb system, or poor matrix-matching between unknowns and reference materials. Zircons with excessive heterogeneity stemming from complex age zonation, abundant radiation damage, or fluid and crystal inclusions rarely generate reliable and meaningful grains. Thus, zircons with 206Pb/238U age uncertainties greater than 5% (at the 1σ uncertainty level) or 207Pb/206Pb age uncertainties greater than 10% (ibid.) were automatically excluded.
Herein we employ a method that benefits from the objectivity of automatic and systematic data selection followed by grain-by-grain assessment of age-depth profiles.

Processing began with the import of individual .FIN2 files written from .DAT and .INF files acquired from analysis of each unknown or reference zircon and its associated baseline and washout signals into the time-constrained reference frame of the IgorPro environment. Following data import, integration windows for baseline and ablatant signals were selected automatically by trimming 19 s (30 s for T0, TM1, TM2, and T6) from the end of each data file for baseline (aka background or blank) integrations, and 7 s and 3 s respectively from the start and end of each data file for ablation signals. Small offsets in analytical start times caused by operator error or computational delays compiling prior analyses’ data occasionally yielded inaccurately auto-selected integration windows. The occasional ablation of epoxy in insufficiently ground zircons or small zircons drilled through during standard ablation durations yielded similarly inappropriate windows. Manual adjustment of these windows was achieved by grain-by-grain data inspection, as was the elimination of analyses of grains known not to be zircon (e.g. by excessively low or unsteady signals, etc.). In the case of the former scenario, whenever possible care was taken to ensure that the start time of each ablatant integration window was spatially equivalent to those of grains with auto-selected windows in order to optimize the accuracy of down-hole fraction correction models (see below).

Following data import, selection, and inspection of integration windows, Iolite-based data reduction involved: (1) subtraction of background signals from signals using an automatic (best-fit: see Paton et al. 2010) interpolation model; (2) determination of appropriate downhole-fractionation correction models by separately stacking the 206Pb/238U and 207Pb/235U (and 208Pb/232Th for T0, TM1, TM2, T6) downhole ratios of each of the primary reference zircon analyses, calculating best-fit exponential curves to those stacked datasets, and applying the resulting models to transform the isotopic ratios of analyzed ‘unknown’ zircons, ideally to optimize ratio steadiness; (3) estimation and correction of instrumental age-offsets and drift by comparison of determined (raw) and accepted (i.e. ID-TIMS) isotopic ratios of the primary reference zircon; and (4) calculation of final ages and values, including (a) propagated uncertainties determined from analyses of the primary reference zircon as pseudo-secondary standards, progressively removing them individually from the dataset, reprocessing the data, and calculating uncertainty, and (b) error correlations using the IgorPro StatsCorrelation function. See Paton et al. (2010) for further clarification and discussion of methods of Iolite data reduction of U-Pb zircon data.
The aforementioned post-acquisition data processing in Iolite outputs 49 additional intermediate and final channels of data, including raw and corrected ratios and calculated ages using various relevant combinations of the seven input channels. Upon this processing, the steadiness of relevant daughter/parent (206Pb/238U) and daughter/daughter ratios (207Pb/206Pb) of each unknown were examined.
Upon differentiating clearly inherited xenocrysts or detrital zircons (i.e. those with ages >30 Ma) from candidate first-cycle volcanogenic zircon, we calculated the weighted-mean ages and uncertainties, and accompanying mean squares of weighted deviates (MSWD) from each sample’s zircon age population(s). Mean spot ages were calculated by treating each laser spot as a separate age, regardless of the number of spots acquired from a given crystal. Weighted-mean grain ages were calculated using the average age of each grain’s spots (i.e. when a given crystal was analyzed by more than one laser spot). Mean spot and mean grain age uncertainties were calculated by quadrature.
Each sample’s unfiltered mean spot ages and mean grain ages, and accompanying uncertainties and MSWD, were calculated from all zircon ages after excluding all clearly xenocrystic or detrital grains (i.e. those with ages >30 Ma). Filtered weighted-mean ages were calculated by iteratively excluding any ages outside two standard deviations of the unfiltered population. In the case of samples having multiple young (<30 Ma) age populations as indicated by subpopulations with non-overlapping 2 sigma uncertainties, we also calculated the weighted-mean age and uncertainty of the youngest population (‘cluster’). We also report the age of the youngest single-spot analysis acquired from each sample (Table 1 in the main text).

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DATA-SPECIFIC INFORMATION FOR: 'Data 2.xlsx'

1. Sample: Around 3 kg of rock tuffaceous levels T3.

2. Geographic location of data colecction: Las Huayquerías del Este, San Carlos department, Mendoza Province, Argentina.

3. Formation, fossil site and coordinates (latitude; longitude) of the collected sample:

T3: Huayquerías Formation, Río Seco de la Isla Grande, 33°58'52.7"S, 68°27'00.8"W

4. Number of sheets: 4

4.1. Sheet 1: Information about conditions of the laboratory.
4.2. Sheet 2: Results of analyses.

A. Number of variables: 20
B. Tipe of case: spots (sample point) on zircon crystals through laser ablation
C. Number of cases/rows in T3: 80
D. Variable List:
* Th (ppm) [Chemical composition]: The concentration of Th measured in the zircon crystal
* U (ppm) [Chemical composition]: The concentration of uranium measured in the zircon crystal

* Th/U (mass) [Chemical composition]: The relative concentrations of Th with respect to uranium measured in the zircon crystal

* 207Pb/235U [Radiogenic ratios]: The relative abundance of 207Pb with respect to 235U measured in the zircon crystal
* 2ѳ [Radiogenic ratios]: The 2s uncertainty of the measured 207Pb/235U ratio in the zircon crystal
* 206Pb/238U [Radiogenic ratios]: The relative abundance of 206Pb with respect to 238U measured in the zircon crystal
* 2ѳ [Radiogenic ratios]: The 2s uncertainty of the measured 206Pb/238U ratio in the zircon crystal
* 207Pb/206Pb [Radiogenic ratios]: The relative abundance of 207Pb with respect to 206Pb measured in the zircon crystal
* 2ѳ [Radiogenic ratios]: The 2s uncertainty of the measured 207Pb/206Pb ratio in the zircon crystal
* Rho XY [Radiogenic ratios]:
* Rho YZ [Radiogenic ratios]:
* 206Pb/238U [Isotopic age (Ma)]: The apparent age of the zircon crystal in millions of years ago (Ma) when calculated from the 206Pb / 238U ratio measured from the zircon crystal. For crystals younger than ca. 1000 Ma, this apparent age is the most reliable
* 2ѳ [Isotopic age (Ma)]: The 2s uncertainty of the measured 206Pb/238U ratio in the zircon crystal
* 207Pb/235U [Isotopic age (Ma)]: The apparent age of the zircon crystal in millions of years ago (Ma) when calculated from the 207Pb / 235U ratio measured from the zircon crystal

* 2ѳ [Isotopic age (Ma)]: The 2s uncertainty of the measured 207Pb/235U ratio in the zircon crystal
* 207Pb/206Pb [Isotopic age (Ma)]: The apparent age of the zircon crystal in millions of years ago (Ma) when calculated from the 207Pb / 206Pb ratio measured from the zircon crystal. For crystals older than ca. 1000 Ma, this apparent age is the most reliable
* 2ѳ [Isotopic age (Ma)]: The 2s uncertainty of the measured 207Pb/206Pb ratio in the zircon crystal

* Preferred Age [Recommended Age]: Preferred (or recommended) age of the isotopic values obtained for each spot
* 2ѳ [Recommended Age]: The 2s uncertainty of the preferred age
* Disc. % (206/238)/(207/235): The degree of concordance between apparent ages calculated from the 206Pb / 238U ratio relative to those calculated from the 207Pb / 235U ratio, expressed as a percentage of the former divided by the latter

E. Missing data codes: None

F. Specialized formats or other abbreviations used: None

4.3. Sheet 3: Graphical results.

4.4. Sheet 4: Information provided by the LA.TE. ANDES S.A. laboratory on the processing of this sample.

5. Methodology for data acquisition

We sampled one tuffaceous level for dating (T3), collecting c. 3 kg of rock, across the Huayquerías, Tunuyán, and Bajada Grande Formation. The tuff levels were georeferenced using Global Positioning System (GPS).

Sample T3 was prepared and analysed by laser-ablation inductively coupled plasma mass-spectrometry by La.Te. Andes laboratory, Salta Province (Argentina). Zircon concentrates were obtained from samples using gravimetric, magnetic, and optical techniques (Fig. S5). Suitability for analysis was evaluated based on the mineralogy of each sample in the heavy mineral fraction and the morphological characteristics of the mineral phases, especially regarding the quantity and quality of zircons. The laboratory provided details of sample preparation, analysis, reduction, and filtering, as well as the age, isotopic ratio, and related data, and are included in Romano et al. (2023, data 2).

Information provided by the LA.TE. ANDES S.A. laboratory on the processing of this sample can be found in sheet 4 of Data 2.

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DATA-SPECIFIC INFORMATION FOR: 'Data 3.xlsx'

1. Samples: Fossil specimens.

2. Geographic location of data colecction: Las Huayquerías del Este, San Carlos department, Mendoza Province, Argentina.

3. Number of sheets: 3

3.1. Sheet 1: Vertebrates: Information about the collected fossil vertebrate specimens.
A. Number of variables: 15
B. Number of cases/rows: 1136
C. Variable List:
* Collection no.: Collection Number of each specimen housed in the repository of the Colección de Paleontología de Vertebrados del Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales (IANIGLA-PV) in Mendoza, Mendoza Province, Argentina.
* Class: Taxonomic Class to which the fossil specimen belongs
* Superorder/Order: Taxonomic Superorder/Order to which the fossil specimen belongs
* Suborder/Infraorder/Superfamily: Taxonomic Suborder/Infraorder/Superfamily to which the fossil specimen belongs
* Family: Taxonomic Family to which the fossil specimen belongs
* Subfamily/Tribu: Taxonomic Subfamily/Tribu to which the fossil specimen belongs
* Genus: Taxonomic Genus to which the fossil specimen belongs
* Species/Taxon: Taxonomic Species to which the fossil specimen belongs or the highest level of systematic determination achieved
* Formation: Formation (lithostratigraphic unit) in which the fossil specimen was collected
* Section: Stratigraphic section in which the specimen was collected
* Fossil site (original names): Original name of the fossiliferous site where the specimen was collected
* Latitude: Latitude coordinates where the specimen was collected (WGS 84 datum , World Geodetic System 1984)
* Longitude: Longitude coordinates where the specimen was collected (WGS 84 datum , World Geodetic System 1984)
* Taxonomic justification: Description of the fossil specimen upon which its taxonomic assignment is based
* Determinated by: Author responsible for the taxonomic determination or publication where it is documented

D. Missing data codes: None

E. Specialized formats or other abbreviations used: None

3.2. Sheet 2: Footprints: Information about the collected fossil footprints.

A. Number of variables: 10
B. Number of cases/rows: 2
C. Variable List:

* Collection no.: Collection Number of each specimen housed in the repository of the Colección de Paleontología de Vertebrados del Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales (IANIGLA-PV) in Mendoza, Mendoza Province, Argentina.
* Material: Type of material used for replication to preserve the specimen
* Ichnogenus: Taxonomic Ichnogenus to which the fossil specimen belongs
* Ichnotaxa: Taxonomic Species to which the fossil specimen belongs
* Formation: Formation (lithostratigraphic unit) in which the fossil specimen was collected
* Section: Stratigraphic section in which the specimen was collected
* Fossil site (original names): Original name of the fossiliferous site where the specimen was collected
* Latitude: Latitude coordinates where the specimen was collected (WGS 84 datum , World Geodetic System 1984)
* Longitude: Longitude coordinates where the specimen was collected (WGS 84 datum , World Geodetic System 1984)
* Determinated by: Author responsible for the taxonomic determination or publication where it is documented

D. Missing data codes: None
E. Specialized formats or other abbreviations used: None

3.3. Sheet 3: Eggshells: Information about the collected fossil eggshells.
A. Number of variables: 9
B. Number of cases/rows: 20
C. Variable List:
* Collection no.: Collection Number of each specimen housed in the repository of the Colección de Paleontología de Vertebrados del Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales (IANIGLA-PV) in Mendoza, Mendoza Province, Argentina.
* Taxon: The highest level of systematic determination achieved
* Formation: Formation (lithostratigraphic unit) in which the fossil specimen was collected
* Section: Stratigraphic section in which the specimen was collected
* Fossil site (original names): Original name of the fossiliferous site where the specimen was collected
* Latitude: Latitude coordinates where the specimen was collected (WGS 84 datum , World Geodetic System 1984)
* Longitude: Longitude coordinates where the specimen was collected (WGS 84 datum , World Geodetic System 1984)
* Taxonomic justification: Description of the fossil specimen upon which its taxonomic assignment is based
* Determinated by: Author responsible for the taxonomic determination or publication where it is documented

D. Missing data codes: n/a indicates that data on the taxonomy of the specimen is not available or does not correspond
E. Specialized formats or other abbreviations used: None
4. Methodology for data acquisition

More than 1100 vertebrate specimens, now housed at IANIGLA-PV, were collected in situ over a ten-year period (2013–2019, 2022) from 21 different fossiliferous sites and stratigraphic levels in the Huayquerías and Tunuyán fms, Mendoza Province, Argentina. The collected specimens, with few exceptions, were georeferenced and their levels of origin were identified. Most specimens were determined by comparison with materials in Argentinean collections or bibliographic data, while others represent new taxa that will be described in future.

The file contains data for each specimen including Collection Number, Taxonomy, Formation and section of provenance, fossil site of origin, GPS coordinates of Latitude and Longitude, and a brief taxonomic justification.

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DATA-SPECIFIC INFORMATION FOR: 'Data 4.xlsx'

1. Number of sheets: 28

1.1. Sheet 1: Fm - Original - taxa: Raw presence-absence data matrix for the different taxa identified in the Huayquerías and Tunuyán formations of the Huayquerías del Este
A. Number of variables: 3
B. Number of cases/rows: 85
C. Variable List:
* Taxa: Taxonomic determination
* Huayquerías Fm: Taxon present (1) or absent (0) in the Huayquerías Formation
* Tunuyán Fm: Taxon present (1) or absent (0) in the Tunuyán Formation

1.2. Sheet 2: Fm - Per1App1OpA - taxa: Presence-absence data matrix for the different taxa identified in the Huayquerías and Tunuyán formations of the Huayquerías del Este applying the scenario Per1App1OpA (see below)
A. Number of variables: 3
B. Number of cases/rows: 71
C. Variable List:
* Taxa: Taxonomic determination
* Huayquerías Fm: Taxon present (1) or absent (0) in the Huayquerías Formation
* Tunuyán Fm: Taxon present (1) or absent (0) in the Tunuyán Formation

1.3. Sheet 3: Fm - Per1App1OpB - taxa: Presence-absence data matrix for the different taxa identified in the Huayquerías and Tunuyán formations of the Huayquerías del Este applying the scenario Per1App1OpB (see below)
A. Number of variables: 3
B. Number of cases/rows: 88
C. Variable List:
* Taxa: Taxonomic determination
* Huayquerías Fm: Taxon present (1) or absent (0) in the Huayquerías Formation
* Tunuyán Fm: Taxon present (1) or absent (0) in the Tunuyán Formation

1.4. Sheet 4: Fm - Per2App1OpA - taxa: Presence-absence data matrix for the different taxa identified in the Huayquerías and Tunuyán formations of the Huayquerías del Este applying the scenario Per2App1OpA (see below)
A. Number of variables: 3
B. Number of cases/rows: 72
C. Variable List:
* Taxa: Taxonomic determination
* Huayquerías Fm: Taxon present (1) or absent (0) in the Huayquerías Formation
* Tunuyán Fm: Taxon present (1) or absent (0) in the Tunuyán Formation

1.5. Sheet 5: Fm - Per2App1OpB - taxa: Presence-absence data matrix for the different taxa identified in the Huayquerías and Tunuyán formations of the Huayquerías del Este applying the scenario Per2App1OpB (see below)

A. Number of variables: 3
B. Number of cases/rows: 90
C. Variable List:
* Taxa: Taxonomic determination
* Huayquerías Fm: Taxon present (1) or absent (0) in the Huayquerías Formation
* Tunuyán Fm: Taxon present (1) or absent (0) in the Tunuyán Formation

1.6. Sheet 6: Fm - Original - Genera: Raw presence-absence data matrix for the different genera identified in the Huayquerías and Tunuyán formations of the Huayquerías del Este
A. Number of variables: 3
B. Number of cases/rows: 50
C. Variable List:
* Genus: Genus-level determination
* Huayquerías Fm: Genus present (1) or absent (0) in the Huayquerías Formation
* Tunuyán Fm: Genus present (1) or absent (0) in the Tunuyán Formation

1.7. Sheet 7: Fm - Per1App1OpA - Genera: Presence-absence data matrix for the different genera identified in the Huayquerías and Tunuyán formations of the Huayquerías del Este applying the scenario Per1App1OpA (see below)

A. Number of variables: 3
B. Number of cases/rows: 46
C. Variable List:
* Genus: Genus-level determination
* Huayquerías Fm: Genus present (1) or absent (0) in the Huayquerías Formation
* Tunuyán Fm: Genus present (1) or absent (0) in the Tunuyán Formation

1.8. Sheet 8: Fm - Per2App1OpA - Genera: Presence-absence data matrix for the different genera identified in the Huayquerías and Tunuyán formations of the Huayquerías del Este applying the scenario Per2App1OpA (see below)

A. Number of variables: 3
B. Number of cases/rows: 46
C. Variable List:
* Genus: Genus-level determination
* Huayquerías Fm: Genus present (1) or absent (0) in the Huayquerías Formation
* Tunuyán Fm: Genus present (1) or absent (0) in the Tunuyán Formation

1.9. Sheet 9: Sections - Original - Genera: Raw presence-absence data matrix for the different genera identified in the sections of the Huayquerías and Tunuyán formations of the Huayquerías del Este

A. Number of variables: 8
B. Number of cases/rows: 50
C. Variable List:
* Genera: Genus-level determination
* HLo: Genus present (1) or absent (0) in the lower section of the Huayquerías Formation (HLo)
* HUp: Genus present (1) or absent (0) in the upper section of the Huayquerías Formation (HUp)
* HuayFm: Genus present (1) or absent (0) in the Huayquerías Formation but without precise stratigraphic correlation
* TunFm: Genus present (1) or absent (0) in the Tunuyán Formation but without precise stratigraphic correlation
* TLo: Genus present (1) or absent (0) in the lower section of the Tunuyán Formation (TLo)
* TMid: Genus present (1) or absent (0) in the middle section of the Tunuyán Formation (TMid)
* TUp: Genus present (1) or absent (0) in the upper section of the Tunuyán Formation (TUp)

1.10. Sheet 10: Sections - Per1App1 - Genera: Presence-absence data matrix for the different genera identified in the sections of the Huayquerías and Tunuyán formations of the Huayquerías del Este applying the scenario Per1App1 (see below)

A. Number of variables: 6
B. Number of cases/rows: 46
C. Variable List:

* Genus: Genus-level determination
* HLo: Genus present (1) or absent (0) in the lower section of the Huayquerías Formation (HLo)

* HUp: Genus present (1) or absent (0) in the upper section of the Huayquerías Formation (HUp)

* TLo: Genus present (1) or absent (0) in the lower section of the Tunuyán Formation (TLo)

* TMid: Genus present (1) or absent (0) in the middle section of the Tunuyán Formation (TMid)

* TUp: Genus present (1) or absent (0) in the upper section of the Tunuyán Formation (TUp)

1.11. Sheet 11: Sections - Per1App2 - Genera: Presence-absence data matrix for the different genera identified in the sections of the Huayquerías and Tunuyán formations of the Huayquerías del Este applying the scenario Per1App2 (see below)

A. Number of variables: 6
B. Number of cases/rows: 46
C. Variable List:
* Genus: Genus-level determination

* HLo: Genus present (1) or absent (0) in the lower section of the Huayquerías Formation (HLo)

* HUp: Genus present (1) or absent (0) in the upper section of the Huayquerías Formation (HUp)

* TLo: Genus present (1) or absent (0) in the lower section of the Tunuyán Formation (TLo)

* TMid: Genus present (1) or absent (0) in the middle section of the Tunuyán Formation (TMid)

* TUp: Genus present (1) or absent (0) in the upper section of the Tunuyán Formation (TUp)

1.12. Sheet 12: Sections - Per1App3 - Genera: Presence-absence data matrix for the different genera identified in the sections of the Huayquerías and Tunuyán formations of the Huayquerías del Este applying the scenario Per1App3 (see below)

A. Number of variables: 6

B. Number of cases/rows: 46
C. Variable List:

* Genus: Genus-level determination

* HLo: Genus present (1) or absent (0) in the lower section of the Huayquerías Formation (HLo)

* HUp: Genus present (1) or absent (0) in the upper section of the Huayquerías Formation (HUp)

* TLo: Genus present (1) or absent (0) in the lower section of the Tunuyán Formation (TLo)

* TMid: Genus present (1) or absent (0) in the middle section of the Tunuyán Formation (TMid)

* TUp: Genus present (1) or absent (0) in the upper section of the Tunuyán Formation (TUp)

1.13. Sheet 13: Sections - Per2App1 - Genera: Presence-absence data matrix for the different genera identified in the sections of the Huayquerías and Tunuyán formations of the Huayquerías del Este applying the scenario Per2App1 (see below)

A. Number of variables: 6
B. Number of cases/rows: 46
C. Variable List:
* Genus: Genus-level determination

* HLo: Genus present (1) or absent (0) in the lower section of the Huayquerías Formation (HLo)

* HUp: Genus present (1) or absent (0) in the upper section of the Huayquerías Formation (HUp)

* TLo: Genus present (1) or absent (0) in the lower section of the Tunuyán Formation (TLo)

* TMid: Genus present (1) or absent (0) in the middle section of the Tunuyán Formation (TMid)

* TUp: Genus present (1) or absent (0) in the upper section of the Tunuyán Formation (TUp)

1.14. Sheet 14: Sections - Per2App2 - Genera: Presence-absence data matrix for the different genera identified in the sections of the Huayquerías and Tunuyán formations of the Huayquerías del Este applying the scenario Per2App2 (see below)
A. Number of variables: 6
B. Number of cases/rows: 46
C. Variable List:
* Genus: Genus-level determination

* HLo: Genus present (1) or absent (0) in the lower section of the Huayquerías Formation (HLo)

* HUp: Genus present (1) or absent (0) in the upper section of the Huayquerías Formation (HUp)

* TLo: Genus present (1) or absent (0) in the lower section of the Tunuyán Formation (TLo)

* TMid: Genus present (1) or absent (0) in the middle section of the Tunuyán Formation (TMid)

* TUp: Genus present (1) or absent (0) in the upper section of the Tunuyán Formation (TUp)

1.15. Sheet 15: Sections - Per2App3 - Genera: Presence-absence data matrix for the different genera identified in the sections of the Huayquerías and Tunuyán formations of the Huayquerías del Este applying the scenario Per2App3 (see below)

A. Number of variables: 6
B. Number of cases/rows: 46
C. Variable List:
* Genus: Genus-level determination

* HLo: Genus present (1) or absent (0) in the lower section of the Huayquerías Formation (HLo)

* HUp: Genus present (1) or absent (0) in the upper section of the Huayquerías Formation (HUp)

* TLo: Genus present (1) or absent (0) in the lower section of the Tunuyán Formation (TLo)

* TMid: Genus present (1) or absent (0) in the middle section of the Tunuyán Formation (TMid)

* TUp: Genus present (1) or absent (0) in the upper section of the Tunuyán Formation (TUp)

1.16. Sheet 16: Sections - Original - Taxa: Raw presence-absence data matrix for the different taxa identified in the sections of the Huayquerías and Tunuyán formations of the Huayquerías del Este
A. Number of variables: 8
B. Number of cases/rows: 85
C. Variable List:

* Taxa: Taxonomic determination

* HLo: Taxon present (1) or absent (0) in the lower section of the Huayquerías Formation (HLo)

* HUp: Taxon present (1) or absent (0) in the upper section of the Huayquerías Formation (HUp)

* HuayFm: Taxon present (1) or absent (0) in the Huayquerías Formation but without precise stratigraphic correlation

* TunFm: Taxon present (1) or absent (0) in the Tunuyán Formation but without precise stratigraphic correlation

* TLo: Taxon present (1) or absent (0) in the lower section of the Tunuyán Formation (TLo)

* TMid: Taxon present (1) or absent (0) in the middle section of the Tunuyán Formation (TMid)

* TUp: Taxon present (1) or absent (0) in the upper section of the Tunuyán Formation (TUp)

1.17. Sheet 17: Sections - Per1App1OpA - Taxa: Raw presence-absence data matrix for the different taxa identified in the sections of the Huayquerías and Tunuyán formations of the Huayquerías del Este applying the scenario Per1App1OpA (see below)
A. Number of variables: 6
B. Number of cases/rows: 69
C. Variable List:

* Taxa: Taxonomic determination

* HLo: Taxon present (1) or absent (0) in the lower section of the Huayquerías Formation (HLo)

* HUp: Taxon present (1) or absent (0) in the upper section of the Huayquerías Formation (HUp)

* TLo: Taxon present (1) or absent (0) in the lower section of the Tunuyán Formation (TLo)

* TMid: Taxon present (1) or absent (0) in the middle section of the Tunuyán Formation (TMid)

* TUp: Taxon present (1) or absent (0) in the upper section of the Tunuyán Formation (TUp)

1.18. Sheet 18: Sections - Per1App2OpA - Taxa: Raw presence-absence data matrix for the different taxa identified in the sections of the Huayquerías and Tunuyán formations of the Huayquerías del Este applying the scenario Per1App2OpA (see below)

A. Number of variables: 6

B. Number of cases/rows: 70

C. Variable List:

* Taxa: Taxonomic determination

* HLo: Taxon present (1) or absent (0) in the lower section of the Huayquerías Formation (HLo)

* HUp: Taxon present (1) or absent (0) in the upper section of the Huayquerías Formation (HUp)

* TLo: Taxon present (1) or absent (0) in the lower section of the Tunuyán Formation (TLo)

* TMid: Taxon present (1) or absent (0) in the middle section of the Tunuyán Formation (TMid)

* TUp: Taxon present (1) or absent (0) in the upper section of the Tunuyán Formation (TUp)

1.19. Sheet 19: Sections - Per1App3OpA - Taxa: Raw presence-absence data matrix for the different taxa identified in the sections of the Huayquerías and Tunuyán formations of the Huayquerías del Este applying the scenario Per1App3OpA (see below)

A. Number of variables: 6

B. Number of cases/rows: 70

C. Variable List:

* Taxa: Taxonomic determination

* HLo: Taxon present (1) or absent (0) in the lower section of the Huayquerías Formation (HLo)

* HUp: Taxon present (1) or absent (0) in the upper section of the Huayquerías Formation (HUp)

* TLo: Taxon present (1) or absent (0) in the lower section of the Tunuyán Formation (TLo)

* TMid: Taxon present (1) or absent (0) in the middle section of the Tunuyán Formation (TMid)

* TUp: Taxon present (1) or absent (0) in the upper section of the Tunuyán Formation (TUp)

1.20. Sheet 20: Sections - Per2App1OpA - Taxa: Raw presence-absence data matrix for the different taxa identified in the sections of the Huayquerías and Tunuyán formations of the Huayquerías del Este applying the scenario Per2App1OpA (see below)

A. Number of variables: 6

B. Number of cases/rows: 71

C. Variable List:

* Taxa: Taxonomic determination

* HLo: Taxon present (1) or absent (0) in the lower section of the Huayquerías Formation (HLo)

* HUp: Taxon present (1) or absent (0) in the upper section of the Huayquerías Formation (HUp)

* TLo: Taxon present (1) or absent (0) in the lower section of the Tunuyán Formation (TLo)

* TMid: Taxon present (1) or absent (0) in the middle section of the Tunuyán Formation (TMid)

* TUp: Taxon present (1) or absent (0) in the upper section of the Tunuyán Formation (TUp)

1.21. Sheet 21: Sections - Per2App2OpA - Taxa: Raw presence-absence data matrix for the different taxa identified in the sections of the Huayquerías and Tunuyán formations of the Huayquerías del Este applying the scenario Per2App2OpA (see below)

A. Number of variables: 6

B. Number of cases/rows: 71

C. Variable List:

* Taxa: Taxonomic determination

* HLo: Taxon present (1) or absent (0) in the lower section of the Huayquerías Formation (HLo)

* HUp: Taxon present (1) or absent (0) in the upper section of the Huayquerías Formation (HUp)

* TLo: Taxon present (1) or absent (0) in the lower section of the Tunuyán Formation (TLo)

* TMid: Taxon present (1) or absent (0) in the middle section of the Tunuyán Formation (TMid)

* TUp: Taxon present (1) or absent (0) in the upper section of the Tunuyán Formation (TUp)

1.22. Sheet 22: Sections - Per2App3OpA - Taxa: Raw presence-absence data matrix for the different taxa identified in the sections of the Huayquerías and Tunuyán formations of the Huayquerías del Este applying the scenario Per2App3OpA (see below)

A. Number of variables: 6

B. Number of cases/rows: 71

C. Variable List:

* Taxa: Taxonomic determination

* HLo: Taxon present (1) or absent (0) in the lower section of the Huayquerías Formation (HLo)

* HUp: Taxon present (1) or absent (0) in the upper section of the Huayquerías Formation (HUp)

* TLo: Taxon present (1) or absent (0) in the lower section of the Tunuyán Formation (TLo)

* TMid: Taxon present (1) or absent (0) in the middle section of the Tunuyán Formation (TMid)

* TUp: Taxon present (1) or absent (0) in the upper section of the Tunuyán Formation (TUp)

1.23. Sheet 23: Sections - Per1App1OpB - Taxa: Raw presence-absence data matrix for the different taxa identified in the sections of the Huayquerías and Tunuyán formations of the Huayquerías del Este applying the scenario Per1App1OpB (see below)

A. Number of variables: 6

B. Number of cases/rows: 85

C. Variable List:

* Taxa: Taxonomic determination

* HLo: Taxon present (1) or absent (0) in the lower section of the Huayquerías Formation (HLo)

* HUp: Taxon present (1) or absent (0) in the upper section of the Huayquerías Formation (HUp)

* TLo: Taxon present (1) or absent (0) in the lower section of the Tunuyán Formation (TLo)

* TMid: Taxon present (1) or absent (0) in the middle section of the Tunuyán Formation (TMid)

* TUp: Taxon present (1) or absent (0) in the upper section of the Tunuyán Formation (TUp)

1.24. Sheet 24: Sections - Per1App2OpB - Taxa: Raw presence-absence data matrix for the different taxa identified in the sections of the Huayquerías and Tunuyán formations of the Huayquerías del Este applying the scenario Per1App2OpB (see below)

A. Number of variables: 6

B. Number of cases/rows: 86

C. Variable List:

* Taxa: Taxonomic determination

* HLo: Taxon present (1) or absent (0) in the lower section of the Huayquerías Formation (HLo)

* HUp: Taxon present (1) or absent (0) in the upper section of the Huayquerías Formation (HUp)

* TLo: Taxon present (1) or absent (0) in the lower section of the Tunuyán Formation (TLo)

* TMid: Taxon present (1) or absent (0) in the middle section of the Tunuyán Formation (TMid)

* TUp: Taxon present (1) or absent (0) in the upper section of the Tunuyán Formation (TUp)

1.25. Sheet 25: Sections - Per1App3OpB - Taxa: Raw presence-absence data matrix for the different taxa identified in the sections of the Huayquerías and Tunuyán formations of the Huayquerías del Este applying the scenario Per1App3OpB (see below)

A. Number of variables: 6

B. Number of cases/rows: 87

C. Variable List:

* Taxa: Taxonomic determination

* HLo: Taxon present (1) or absent (0) in the lower section of the Huayquerías Formation (HLo)

* HUp: Taxon present (1) or absent (0) in the upper section of the Huayquerías Formation (HUp)

* TLo: Taxon present (1) or absent (0) in the lower section of the Tunuyán Formation (TLo)

* TMid: Taxon present (1) or absent (0) in the middle section of the Tunuyán Formation (TMid)

* TUp: Taxon present (1) or absent (0) in the upper section of the Tunuyán Formation (TUp)

1.26. Sheet 26: Sections - Per2App1OpB - Taxa: Raw presence-absence data matrix for the different taxa identified in the sections of the Huayquerías and Tunuyán formations of the Huayquerías del Este applying the scenario Per2App1OpB (see below)

A. Number of variables: 6

B. Number of cases/rows: 89

C. Variable List:

* Taxa: Taxonomic determination

* HLo: Taxon present (1) or absent (0) in the lower section of the Huayquerías Formation (HLo)

* HUp: Taxon present (1) or absent (0) in the upper section of the Huayquerías Formation (HUp)

* TLo: Taxon present (1) or absent (0) in the lower section of the Tunuyán Formation (TLo)

* TMid: Taxon present (1) or absent (0) in the middle section of the Tunuyán Formation (TMid)

* TUp: Taxon present (1) or absent (0) in the upper section of the Tunuyán Formation (TUp)

1.27. Sheet 27: Sections - Per2App2OpB - Taxa: Raw presence-absence data matrix for the different taxa identified in the sections of the Huayquerías and Tunuyán formations of the Huayquerías del Este applying the scenario Per2App2OpB (see below)

A. Number of variables: 6

B. Number of cases/rows: 89

C. Variable List:

* Taxa: Taxonomic determination

* HLo: Taxon present (1) or absent (0) in the lower section of the Huayquerías Formation (HLo)

* HUp: Taxon present (1) or absent (0) in the upper section of the Huayquerías Formation (HUp)

* TLo: Taxon present (1) or absent (0) in the lower section of the Tunuyán Formation (TLo)

* TMid: Taxon present (1) or absent (0) in the middle section of the Tunuyán Formation (TMid)

* TUp: Taxon present (1) or absent (0) in the upper section of the Tunuyán Formation (TUp)

1.28. Sheet 28: Sections - Per2App3OpB - Taxa: Raw presence-absence data matrix for the different taxa identified in the sections of the Huayquerías and Tunuyán formations of the Huayquerías del Este applying the scenario Per2App3OpB (see below)

A. Number of variables: 6

B. Number of cases/rows: 89

C. Variable List:

* Taxa: Taxonomic determination

* HLo: Taxon present (1) or absent (0) in the lower section of the Huayquerías Formation (HLo)

* HUp: Taxon present (1) or absent (0) in the upper section of the Huayquerías Formation (HUp)

* TLo: Taxon present (1) or absent (0) in the lower section of the Tunuyán Formation (TLo)

* TMid: Taxon present (1) or absent (0) in the middle section of the Tunuyán Formation (TMid)

* TUp: Taxon present (1) or absent (0) in the upper section of the Tunuyán Formation (TUp)
```

2. Missing data codes: None

3. Specialized formats or other abbreviations used: None

4. Methodology for data acquisition

Biostratigraphic analysis

    We divided the Huayquerías-Tunuyán stratigraphic succession to explore possible faunal turnover across the sequence. The Huayquerías Fm. was divided into a lower section (HLo, < c. 6.2 Ma) and an upper section (HUp, > c. 6.2 Ma), based on independent geochronological dates. The Tunuyán Fm. was divided into three sections of equivalent thickness, denominated TLo (lower), TMid (middle), and TUp (upper).

Similarity analysis

    Different possible scenarios were considered in the analysis. We applied two different perspectives to deal with problems arising from taxa with open nomenclature. In perspective 1 (Per1), ambiguous taxa were excluded from the analysis when another unambiguous taxon existed, whereas in perspective 2 (Per2), we considered taxa with open nomenclature as unambiguously belonging to the unqualified taxon (cf. or aff.) to see how the results could be affected in case the presence of such taxa was corroborated in the future in different sections of the sequence where the presence of such taxon could not be confirmed for now due to the lack of intraspecific variability studies in some cases. In addition, both perspectives follow three different approaches. The first approach (App1) employs the raw data; the second (App2) includes ‘Lazarus taxa’. We consider that the absences of certain taxa in some levels may be caused by biases in the record, due to both the environmental monotony observed in the sedimentary

    sequence and the geological similarity between the different sections (see section Geological settings; in the main text), discarding also biogeographical differences in the Huayquerías del Este area, or due to a lower sampling of some sections. The third approach (App3) considers taxa without precise stratigraphic correlation collected from the Huayquerías or Tunuyán fms as they come from HUp or TLo when they were recorded in at least one section of the Tunuyán or Huayquerías Fm., respectively. This situation affects, on the one hand, 90 specimens from the Huayquerías Fm. collected in Huayquerías de la Horqueta Norte and Sur. The taxa represented there are considered as belonging to HUp as long as they appear in the Tunuyán Fm. from another fossil site; and, on the other hand, it affects 21 specimens collected from the Tunuyán Fm. in RS del Agua Escondida. The taxa represented there are considered as TLo if they occur in the Huayquerías Fm. of another fossil site. In this way we explore the effect of 

    placing these fossils following the hypotheses about the correlation of these sites that we considered more probable (e.g. the regional geological observations regarding the arrangement of the strata and stratigraphic contacts of each of these sites). Furthermore, analyses at the species level were performed under two different alternatives: option A (OpA), the raw data; and option B (OpB), when two or more species of the same genus were identified, the taxonomic category of the genus was included as a separate entry. The latter aims to reduce the differences caused by the difficulty of determining specimens at the species level, as genera are less affected by the problems of assessing intraspecific variability in fossils. In addition, similarity analyses were performed both at the genus level only and genus/species level.

    For comparisons between stratigraphic formations, we applied the two perspectives (Per1–2), the first approach (App1), and option A (OpA) at the two levels of analysis, while the second alternative (OpB) was also explored with genus/species matrices. For comparisons between each pair of sections, the two perspectives (Per1–2), three approaches (App1–3), and option A (OpA) at only genus matrices, and all possible scenarios (Per1–2, App1–3, and OpA–B) at genus/species matrices were explored.

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