Data from: Extreme neck elongation evolved despite strong developmental constraints in bizarre Triassic reptiles – implication for neck modularity in archosaurs
Data files
May 07, 2024 version files 267.59 KB
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Macrocnemus_bassanii_raw.dat
15.92 KB
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Macrocnemus_fuyuanensis_raw.dat
12.98 KB
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Prolacerta_broomi_raw.dat
7 KB
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Prolacerta_broomi_supplement_raw.dat
14.58 KB
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Protorosaurus_speneri_raw.dat
4.72 KB
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README.md
2.31 KB
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Tanystropheus_conspicuus_2Dvs3D_combined_transformed.dat
107.67 KB
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Tanystropheus_spp._raw.dat
102.42 KB
Abstract
The Triassic radiation of vertebrates saw the emergence of the modern vertebrate groups, as well as numerous extinct animals exhibiting conspicuous, unique anatomical characteristics. Among these, members of Tanystropheidae (Reptilia: Archosauromorpha) displayed cervical vertebral elongation to an extent unparalleled in any other vertebrate. Tanystropheids were exceptionally ecologically diverse and had a wide spatial and temporal distribution. This may have been related to their neck anatomy, yet its evolution and functional properties remain poorly understood. We used geometric morphometrics to capture the intraspecific variation between the vertebrae comprising the cervical column among early archosauromorphs, to trace the evolutionary history of neck elongation in these animals. Our results show that the cervical series of these reptiles can be divided into modules corresponding to those of extant animals. Tanystropheids achieved neck elongation through somite elongation and a shift between cervical and thoracic regions, without presacral vertebrae count increase - contrary to crown archosaurs. This suggests a peculiar developmental constraint that strongly affected the evolution of tanystropheids. The data obtained just at the base of the archosauromorph phylogenetic tree is crucial for further studies on the modularity of vertebral columns of not only Triassic reptile groups but extant and other extinct animals as well.
README: Data from: Extreme neck elongation evolved despite strong developmental constraints in bizarre Triassic reptiles – implication for neck modularity in archosaurs
This dataset contains the raw (untransformed) x/y data for the landmarks digitised onto the archosauromorph vertebrae photographs in the tpsDig v2.31 software.
Description of the Data and file structure
The dataset contains seven .dat files that correspond to data gathered for four genera of Triassic archosauromorphs:
Macrocnemus_bassanii_raw - Macrocnemus bassanii. Contains xy data for 83 landmark points gathered from 2D images.
Macrocnemus_fuyuanensis_raw - Macrocnemus fuyuanensis. Contains xy data for 83 landmark points gathered from 2D images.
Prolacerta_broomi_raw - Prolacerta broomi. Contains xy data for 83 landmark points gathered from 2D images.
Prolacerta_broomi_supplement_raw - Prolacerta broomi. Contains xy data for 64 landmark points gathered from 2D images. The landmark set was reduced from 83 to 64 points to allow for a broader sampling of damaged specimens.
Protorosaurus_speneri_raw - Protorosaurus speneri. Contains xy data for 83 landmark points gathered from 2D images.
Tanystropheus_spp._raw - Tanystropheus spp. (T. ‘conspicuus’, hydroides, longobardicus, sp.). Contains xy data for 83 landmark points gathered from 2D images.
Tanystropheus_conspicuus_2Dvs3D_combined_transformed - Tanystropheus spp. (T. ‘conspicuus’, hydroides, longobardicus, sp.). Contains xyz data for 83 landmark points gathered from 2D images and 3D models. A cell with the third dimension (z) value of 0 was added to each of the 2D landmarks. This allowed both datasets to be superimposed together. They were then mean cantered by removing means from the respective shape data (2D or 3D) in each column. The rows marked with red are two-dimensional data, while the rows marked with blue are three-dimensional data. Both of these have been transformed by Procrustes superimposition.
Within the data set, each row represents a singular vertebra, with a name coded as X(first letter of the genus name)xyz(first three letter of the species name)_specimen_number_xy(position in the neck - if possible to determine).
Sharing/access Information
NA
Methods
This dataset contains all of the untransformed morphometric data used in the study Rytel et al. 2024.
Landmarks (LMs) used in the main (two-dimensional) analysis were digitised onto specimen photographs in the tpsDig v2.31 software in accordance with a landmark set encompassing the outline of the vertebrae in lateral view. The landmarks cover the maximal extent of characteristic osteological features – vertebral centrum, neural spine, pre- and postzygapophysis. These points are considered to be homologous for all of the studied taxa. The chosen landmarks (together with semilandmarks) cover most of the shape of the vertebrae. Moreover, they are (aside from LM5 in some cases) extremely easy to locate, providing high repeatability potential.
Exact definitions of the true landmarks contained within the landmark set are listed below:
1. Ventral-posterior edge of the centrum
2. Ventral-anterior edge of the centrum
3. Point of maximum curvature between prezygapophysis and the anterior edge of the centrum
4. Dorsal-anterior edge of the prezygapophysis
5. Point of maximum curvature between prezygapophysis and neural spine
6. Dorsal-anterior edge of the neural spine
7. Dorsal-posterior edge of the neural spine
8. Dorsal-posterior edge of the postzygapophysis
Semilandmark lines encompassed the following number of semilandmarks: 16 ( between LM1 and LM2), 7 (LM2-LM3), 8 (LM3-LM4), 9 (LM4-L5), 6 (LM5-LM6), 14 (LM6-LM7), 13 (LM7-LM8).
Most of the other data are contained within the associated manuscript and the supplementary material.
Usage notes
The .dat files can be opened with the free PAST software for Windows only (https://past.en.lo4d.com/windows).
It can also be opened with a simple text editor.