Tanystropheus neck study suffers from taxon exclusion

Rytel et al
“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.” = tanystropheids (Fig 1).

Unfortunately, due to taxon exclusion, Rytel et al were comparing lepidosaurormorph lepidosaur (tanystropheids, Fig 1) with convergently similar, but unrelated archosauromorph protorosaurs (Fig 2).

Tanystropheus and kin going back to Huehuecuetzpalli. ” data-image-caption=”

Figure 1. Tanystropheus and kin going back to Huehuecuetzpalli.

” data-medium-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2011/10/tanystropheus-and-kin.jpg?w=240″ data-large-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2011/10/tanystropheus-and-kin.jpg?w=584″ class=”size-full wp-image-2566″ src=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2011/10/tanystropheus-and-kin.jpg” alt=”Tanystropheus and kin going back to Huehuecuetzpalli.” width=”584″ height=”730″ />

Figure 1. Tanystropheus and kin going back to Huehuecuetzpalli from 2011.

Rytel et al wrongly considered
tanystropheids members of the Archosauromorpha. This is a traditional academic myth invalidated by testing in the large reptile tree (LRT, 2319 taxa) and by Peters 2007. So Rytel et al correctly compared Tanystropheus to Macrocnemus, but incorrectly compared Tanystropheus to Proganochelys, Protorosaurus (Fig 2), Prolacerta, Plateosaurus, Gallus and Crocodylus. Related taxa in the LRT include Huehuecuetzpalli (Fig 1), a taxon not mentioned by the authors.

On a broadly similar note, an Oculudentavis paper
(Xing et al 2020) was retracted when it was noted that the purported bird/archosaur was actually a lepidosaur, paralleling the situation in today’s post. According to Wikipedia, “The decision of the authors to assume that Oculudentavis is a bird a priori, without testing other possible positions, for their morphological description and phylogenetic analysis also was called “illogical” by Wang et al., who noted that the rejection of this hypothesis would compromise the paper’s conclusions and significance.”

Unfortunately ‘without testing‘ remains an academically approved method in 2024. Perhaps the only exception was the 2020 Oculudentavis paper.

Oculudentavis is related to Cosesaurus, Langobardisaurus, Tanytrachelos and Tanystropheus in order of increasing distance in the LRT.

Peters 2000 made the same mistake
in connecting protorosaurs to tanystropheids because it was ‘common knowledge’ back then. Peters 2007 corrected that mistake by adding taxa.

Figure 5. Several protorosaurs to scale including Pamelaria, Protorosaurus, Prolacerta, Malerisaurus, Boreopricea and Jaxtasuchus. Click to enlarge. ” data-image-caption=”

Figure 5. Several protorosaurs to scale including Pamelaria, Protorosaurus, Prolacerta, Malerisaurus, Boreopricea and Jaxtasuchus. Click to enlarge.

” data-medium-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2015/12/protorosaurs161.jpg?w=300″ data-large-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2015/12/protorosaurs161.jpg?w=584″ class=”wp-image-21341 size-full” src=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2015/12/protorosaurs161.jpg” alt=”Figure 5. Several protorosaurs to scale including Pamelaria, Protorosaurus, Prolacerta, Malerisaurus, Boreopricea and Jaxtasuchus. Click to enlarge.” width=”1573″ height=”473″ />

Figure 2. Several protorosaurs to scale including Pamelaria, Protorosaurus, Prolacerta, Malerisaurus, Boreopricea and Jaxtasuchus. Click to enlarge.

The authors reported,
“If we consider Protorosaurus speneri as an outgroup for all other archosauromorphs, with five postaxial cervical vertebrae divided into three subregions, and using parsimony, we can recreate a hypothetical history of the specialized neck anatomy evolution in tanystropheids and some of their close archosauromorph relatives.”

Indeed, Protorosaurus is a stem archosauriform within the Archosauromorpha in the LRT. So there is no need to ‘consider’. Testing in the LRT and its predecessors have determined that hypothesis of interrelationships.

Unfortunately after testing, Tanystropheus is not a stem or basal archosauriform/archosauromorph. Protorosaurs and tanystropheids are convergent in several regards (Figs 1, 2), but are not related. Taxon exclusion is once again the simple reason for the present academic confusion.

Add taxa to untangle this web for yourself. Remove academic blinders by testing.

References
Peters D 2000. A Redescription of Four Prolacertiform Genera and Implications for Pterosaur Phylogenesis. Rivista Italiana di Paleontologia e Stratigrafia 106 (3): 293–336.
Peters D 2007.The origin and radiation of the Pterosauria. In D. Hone ed. Flugsaurier. The Wellnhofer pterosaur meeting, 2007, Munich, Germany. p. 27.
Rytel A, Böhmer C, SpiekmanSNF and Tałanda M. 2024 Extreme neck elongation evolved  despite strong developmental constraints in bizarre Triassic reptiles—implications for neck modularity in archosaurs. R. Soc. Open Sci. 11: 240233. https://doi.org/10.1098/rsos.240233
Xing L, O’Connor JK,; Schmitz L, Chiappe LM, McKellar RC, Yi Q and Li G 2020. Hummingbird-sized dinosaur from the Cretaceous period of Myanmar. Nature. 579 (7798): 245–249.

Tanystropheus papers:
Bassani F 1886. Sui Fossili e sull’ età degli schisti bituminosi triasici di Besano in Lombardia. Atti della Società Italiana di Scienze Naturali 19:15–72.
Li C 2007. A juvenile Tanystropheus sp.(Protoro sauria: Tanystropheidae) from the Middle Triassic of Guizhou, China. Vertebrata PalAsiatica 45(1): 37-42.
Meyer H von 1847–55. Die saurier des Muschelkalkes mit rücksicht auf die saurier aus Buntem Sanstein und Keuper; pp. 1-167 in Zur fauna der Vorwelt, zweite Abteilung. Frankfurt.
Nosotti S 2007. Tanystropheus longobardicus (Reptilia, Protorosauria: Reinterpretations of the anatomy based on new specimens from the Middle Triassic of Besano (Lombardy, Northern Italy). Memorie della Società Italiana di Scienze Naturali e del Museo Civico di Storia Naturale di Milano, Vol. XXXV – Fascicolo III, pp. 1-88.
Peters D 2005. Suction feeding in a Triassic protorosaur? Science 308(5725): 1112c–1113c DOI 10.1126/science.308.5725.1112c.
Peyer B 1931. Tanystropheus longobardicus Bass sp. Die Triasfauna der Tessiner Kalkalpen. Abhandlungen Schweizerische Paläontologie Gesellschaft 50:5-110.
Rieppel O, Jiang D-Y, Fraser NC, Hao W-C, Motani R, Sun Y-L & Sun ZY 2010. Tanystropheus cf. T. longobardicus from the early Late Triassic of Guizhou Province, southwestern China. Journal of Vertebrate Paleontology 30(4):1082-1089.
Spiekman SNF and Scheyer TM 2019. A taxonomic revision of the genus Tanystropheus (Archosauromorpha, Tanystropheidae). Palaentologia Electronica 22.3.80 PDF
Spiekman SNF et al. (6 co-authors) 2020. Aquatic Habits and Niche Partitioning in the
Extraordinarily Long-Necked Triassic Reptile Tanystropheus. Current Biology 30:1–7. https://doi.org/10.1016/j.cub.2020.07.025
Spiekman SNF, Fraser NC and Scheyer TM 2021. A new phylogenetic hypothesis of Tanystropheidae (Diapsida, Archosauromorpha) and other “protorosaurs”, and its implications for the early evolution of stem archosaurs. PeerJ 9:e11143 DOI 10.7717/peerj.11143
Wild R 1973. Die Triasfauna der Tessiner Kalkalpen XXIII. Tanystropheus longobardicus (Bassani) (Neue Ergebnisse). – Schweizerische Paläontologische Abhandlungen 95: 1-162 plus plates.

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