Data for: Theropod dinosaur diversity of the lower English Wealden: analysis of a tooth-based fauna from the Wadhurst Clay Formation (Lower Cretaceous: Valanginian) via phylogenetic, discriminant and machine learning methods
Data files
Dec 05, 2024 version files 2.83 MB
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Barker_et_al_2024_Wadhurst_Clay_analyses.zip
2.82 MB
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README.md
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Abstract
The Lower Cretaceous Wealden Supergroup of southern England yields a diverse assemblage of theropod dinosaurs, its taxa being represented by fragments in addition to some of the most informative associated skeletons of the European Mesozoic. Spinosaurids, neovenatorid allosauroids, tyrannosauroids, and dromaeosaurids are among the reported Wealden Supergroup clades. However, the majority of relevant specimens are from the Barremian Upper Weald Clay and Wessex formations, and theropod diversity in the older Berriasian—Valanginian Hastings Group has remained poorly known, the fragmentary specimens reported thus far remaining enigmatic both in terms of phylogenetic affinities and sometimes provenance. A better understanding would be welcome given the paucity of Berriasian—Valanginian dinosaurs worldwide. Here, we describe an assemblage of Hastings Group theropod teeth from Valanginian Wadhurst Clay Formation outcrops of the Ashdown Brickworks locality near Bexhill, East Sussex. We subjected these teeth to phylogenetic, discriminant, and machine-learning analyses and found them to include members of Spinosauridae, Tyrannosauroidea, and Dromaeosauridae, in addition to others that remain of uncertain affinity within Coelurosauria. The taxa are distinct from those known from elsewhere in the Wealden Supergroup: the spinosaurid is not Baryonyx, and the tyrannosauroid is not Eotyrannus, for example, but we have not named new taxa at this time. Combined with other findings in the Wadhurst Clay Formation, our study indicates that Valanginian theropod diversity was comparable to that of younger Wealden Supergroup units, implying that the “characteristic” theropod components of Wealden faunas were established early within the deposition of this famous geological succession.
README: Data for: Theropod dinosaur diversity of the lower English Wealden: analysis of a tooth-based fauna from the Wadhurst Clay Formation (Lower Cretaceous: Valanginian) via phylogenetic, discriminant and machine learning methods
https://doi.org/10.5061/dryad.kwh70rzdw
Description of the data and file structure
Morphometric and cladistic data for theropod dental morphotypes I—V were collected via first-hand observation and a DinoLite (AM4113TL) digital microscope. Measurements were taken using a digital caliper and the measuring tools provided in the Dinocapture 2.0 software (v.1.5.48.A).
Files - Barker et al 2024 Wadhurst Clay analyses
Contains 3 folders and 1 .csv file.
"Cladistic" folder containing:
- Individual folders for the phylogenetic analysis of the morphotypes, which include:
- Crown and whole-dentition matrices (.tnt) that run in the phylogenetic software package TNT (v1.6).
- STATS.run script - a TNT script that calculates the consistency index (CI) and retention index (RI) of the recovered trees.
- "Character list and Wadhurst Clay Fm Theropod Teeth Scores.txt" - A .txt document providing the character list used in this study (based on Hendrickx et al., 2020) as well as the character scores for the tooth specimens (inc. the "whole dentition" and "crown only" matrices).
- "Full phylogenetic results.pdf" - A PDF document with the full trees recovered by the phylogenetic results.
"DFA" folder containing:
- Individual folders for each morphotype for the various iterations of the discriminant analyses, based on files from Hendrickx et al. (2020). These contain:
- DAT files that run in PAST 4.0 (note that "no ratios" in file names reflect a lack of ratio-based morphometric variables, e.g. crown base ratio).
- Specimens were analysed using various iterations of the following files:
- "Morpho teeth whole dataset unser" files: Data collected using the whole dataset, with an absence of denticles considered inapplicable.
- "Morpho teeth whole dataset" files: Data collected using the whole dataset, with an arbitrary value of 100 denticles per five mm used for unserrated carinae.
- "Morpho teeth My dataset unser" files: Data collected by a single author, with an absence of denticles considered inapplicable.
- "Morpho teeth My dataset" files: Data collected by a single author, with an arbitrary value of 100 denticles per five mm used for unserrated carinae.
- Large teeth were additionally analysed using the following:
- "Morpho large teeth whole dataset unser" files: Data collected using only large teeth (crown height >20mm) from the whole dataset, with an absence of denticles considered inapplicable.
- "Morpho large teeth whole dataset" files: Data collected using only large teeth (crown height >20mm) from the whole dataset, with an arbitrary value of 100 denticles per five mm used for unserrated carinae.
- "Morpho large teeth My dataset unser" files: Data restricted to large teeth (crown height >20mm) and collected by a single author, with an absence of denticles considered inapplicable.
- "Morpho large teeth My dataset" files: Data restricted to large teeth (crown height >20mm) and collected by a single author, with an arbitrary value of 100 denticles per five mm used for unserrated carinae.
- Small teeth were additionally analysed using the following:
- "Morpho teeth whole dataset small teeth only unser" files: Data collected using only large teeth (crown height <20mm) from the whole dataset, with an absence of denticles considered inapplicable.
- "Morpho teeth whole dataset small teeth only" files: Data collected using only small teeth (crown height <20mm) from the whole dataset, with an arbitrary value of 100 denticles per five mm used for unserrated carinae.
- For Morphotype I (BEXHM 1995.485), additional spinosaur-only datasets were also used, extrapolated from data in Hendrickx et al (2020) and used in Barker et al (2023):
- "All spino all variables dataset" - Dataset restricted to all spinosaur-only specimens using all morphometric variables.
- "All spino dataset no ratios" - Dataset restricted to all spinosaur-only specimens using only non-ratio morphometric variables.
- "Reduced spino all variables" - Dataset restricted to spinosaur-only specimens known from more than a single tooth, using all morphometric variables.
- "Reduced spino dataset no ratios" - Dataset restricted to spinosaur-only specimens known from more than a single tooth, using only non-ratio morphometric variables.
- "Hendrick et al. 2020 Crown measurement datasets with small tooth only.csv": A .csv file containing crown measurement datasets focusing on small teeth (>20mm), extracted from previous works (Hendrickx et al., 2020). All non-ratio values are in millimetres (mm).
- "Results.xml": A formatted Excel worksheet summarising the results of the DFAs.
"Machine Learning" folder
- A Word file detailed the machine learning protocol
- A Word file summarising the machine learning results.
- Note that training data can be found in Hendrickx et al. (2020) and Wills et al. (2023).
"Morphometric data.csv" - a .csv file containing morphometric data for all 5 specimens analysed. Variables based on terminology from Hendrickx et al. (2015). All non-ratio values are in millimetres (mm).
Variables used in the analyses:
- Phylogenetic analyses
- Numerical values (0, 1, 2 ... n) = character states, based on character descriptions from Hendrickx et al. (2020).
- "?" = missing data
- DFAs and Machine Learning analyses
- Morphometric terms from Hendrickx et al. (2015):
- Crown Base Length (CBL)—Maximum mesiodistal extent of the crown base at the level of the cervix
- Crown Base Width (CBW)—Labiolingual extent of the crown base at mid-length, perpendicular to the CBL, and at the level of the cervix
- Crown Height (CH)—Maximum apicobasal extent of the distal margin of the crown. The crown height is taken from the distal-most point of the cervix to the apical-most point of the crown
- Apical Length (AL)—Maximum apicobasal extent of the mesial margin of the crown
- Mid-crown Length (MCL)—Maximum mesiodistal extent of the tooth at mid-height of the crown
- Mid-crown Width (MCW)—Maximum labiolingual extent of the tooth, perpendicular to the MCL, at mid-height of the crown
- Mesial Serrated Carina Length (MSL)—Maximum apicobasal extent of the mesial serrated carina
- Labial Flutes (LAF)—Number of flutes on the labial surface of the crown.
- Lingual Flutes (LIF)—Number of flutes on the lingual surface of the crown
- Crown Angle (CA)—Angle created by the apical length AL and the crown base length (CBL; Smith et al., 2005; Fig. 7C). The crown angle, which can be calculated using the law of cosines
- Mesial Denticle Length (MDL)—Maximum apicobasal extent of a denticle on the mesial carina at two-thirds of the crown height, taken perpendicular to the Mesial Denticle Height at the base of the denticle.
- Distal Denticle Length (DDL)—Maximum apicobasal extent of a denticle on the distal carina at mid-crown, taken perpendicular to the Distal Denticle Height at the base of the denticle
- Additional terms from Wills et al (2023) for the machine learning analyses
- ADM - number of denticles per millimetre at the midpoint of the mesial carina.
- PDM - number of denticles per millimetre at the midpoint of the distal carina.
- "?" = missing data
- "-" = inapplicable metric
References
BARKER, C. T., NAISH, D. and GOSTLING, N. J. 2023. Isolated tooth reveals hidden spinosaurid dinosaur diversity in the British Wealden Supergroup (Lower Cretaceous). PeerJ, 11, e15453.
HENDRICKX, C., MATEUS, O. and ARAÚJO, R. 2015. A proposed terminology of theropod teeth (Dinosauria, Saurischia). Journal of Vertebrate Paleontology, 35, e982797.
HENDRICKX, C., TSCHOPP, E. and D. EZCURRA, M. 2020. Taxonomic identification of isolated theropod teeth: the case of the shed tooth crown associated with Aerosteon (Theropoda: Megaraptora) and the dentition of Abelisauridae. Cretaceous Research, 108, 104312.
WILLS, S., UNDERWOOD, C. J. and BARRETT, P. M. 2023. Machine learning confirms new records of maniraptoran theropods in Middle Jurassic UK microvertebrate faunas. Papers in Palaeontology, 9, e1487.