A New Placodont from the Late Triassic of China

Wang, W., Li, C., Scheyer, T. M., and Zhao, L. 2019. A new species of Cyamodus (Placodontia, Sauropterygia) from the early Late Triassic of south-west China. Journal of Systematic Palaeontology. Link.

Abstract - The Triassic eastern Tethyan faunas have continued to yield numerous specimens of marine reptile taxa in recent years. Nevertheless, compared with other sauropterygian clades, the diversity of placodonts in these faunas is low, and remains of this group are relatively rare in the fossil assemblages. Here, we report a new cyamodontoid specimen (ZMNH M8820) from the early Late Triassic of Guizhou, south-west China. This specimen is a nearly complete skeleton lacking only the forelimbs. It is distinct from other known Chinese placodonts as it features a large skull with remarkably enlarged supratemporal fenestrae and a small and less regularly arranged carapace. Interestingly, this new specimen resembles the European Cyamodus more than any Chinese cyamodontoid genera, particularly when considering the dentition and other cranial morphology. However, it differs from known Cyamodus species in some cranial features (e.g. epipterygoid fully ossified, posttemporal fenestra large, dentition derived) and the absence of a separate pelvic shield. Furthermore, based on an updated data matrix of placodonts, our phylogenetic results support the affinity of this new Chinese specimen with European Cyamodus species, and a new species, Cyamodus orientalis sp. nov., is erected here. This new material represents the first reported Cyamodus specimen in the world that preserves a three-dimensional skull with an associated postcranial skeleton and it extends the distribution of this genus into the early Carnian of the eastern Tethys. The existence of Cyamodus, a nearshore taxon, in south-west China at this time reveals greater similarity and more rapid intercommunication than previously known between western and eastern Tethyan vertebrate faunas, although the palaeobiogeographical origin and migration history of Cyamodontidae – and of other clades of placodont reptiles – are still obscure due to the scarcity of material from the northern and southern margins of the Palaeotethys.

Platypus-like Hupehsuchian from Early Triassic of China

Cheng, L., Motani, R.,  Jiang, D., Yan, C., Tintori, A. and O. Rieppel. 2019. Early Triassic marine reptile representing the oldest record of unusually small eyes in reptiles indicating non-visual prey detection. Scientific Reports 9, number 152. DOI: 10.1038/s41598-018-37754-6

Abstract - The end-Permian mass extinction (EPME) led to reorganization of marine predatory communities, through introduction of air-breathing top predators, such as marine reptiles. We report two new specimens of one such marine reptile, Eretmorhipis carrolldongi, from the Lower Triassic of Hubei, China, revealing superficial convergence with the modern duckbilled platypus (Ornithorhynchus anatinus), a monotreme mammal. Apparent similarities include exceptionally small eyes relative to the body, snout ending with crura with a large internasal space, housing a bone reminiscent of os paradoxum, a mysterious bone of platypus, and external grooves along the crura. The specimens also have a rigid body with triangular bony blades protruding from the back. The small eyes likely played reduced roles during foraging in this animal, as with extant amniotes (group containing mammals and reptiles) with similarly small eyes. Mechanoreceptors on the bill of the animal were probably used for prey detection instead. The specimens represent the oldest record of amniotes with extremely reduced visual capacity, utilizing non-visual cues for prey detection. The discovery reveals that the ecological diversity of marine predators was already high in the late Early Triassic, and challenges the traditional view that the ecological diversification of marine reptiles was delayed following the EPME.

Macropredatory ichthyosaur, Thalattoarchon saurophagis, from the Middle Triassic of Nevada

New in PNAS. I assume by terrestrial apex predators in the Carnian they are thinking about phytosaurs and/or large rauisuchids as they (p. 3) state that "Although large predators such as the rauisuchians Erythrosuchus and Ticinosuchus appear in the terrestrial rock record in the Anisian (Nesbitt, 2011), it has been suggested that full recovery on land was not reached until the Late Triassic, 30 My after the P/T extinction (Sahney & Benton, 2008)" [full references and edit added]. Unfortunately this ignores a good bit of new evidence published since 2008 that has changed our understanding of the timing of recovery on land (Xilousuchus, Nyassasaurus). However, I still think the existance of giant (almost 9 meter long) ichthyosaurs is incredible. More than a decade ago I got to see the 21 meter long holotype specimen of Shastasaurus sikanniensis (Late Triassic, British Columbia) when it was being prepared at the Royal Tyrell Museum. To get a photograph of just the rear portion of the skull I had to stand at the top of a fully extended ladder. I used a meter stick for the scale bar! This new specimen is not quite 9 meters in length, but is still huge as the average is 2-4 meters, and it has 12 cm long teeth.

Fröbisch, N. B., Fröbisch, J., Sander, P. M., Schmitz, L., and O. Rieppel. 2013. Macropredatory ichthyosaur from the Middle Triassic and the origin of modern trophic networks. PNAS Early Edition, January 7, 2013. doi:10.1073/pnas.1216750110

 Abstract - The biotic recovery from Earth’s most severe extinction event at the Permian-Triassic boundary largely reestablished the preextinction structure of marine trophic networks, with marine reptiles assuming the predator roles. However, the highest trophic level of today's marine ecosystems, i.e., macropredatory tetrapods that forage on prey of similar size to their own, was thus far lacking in the Paleozoic and early Mesozoic. Here we report a top-tier tetrapod predator, a very large (>8.6 m) ichthyosaur from the early Middle Triassic (244 Ma), of Nevada. This ichthyosaur had a massive skull and large labiolingually flattened teeth with two cutting edges indicative of a macropredatory feeding style. Its presence documents the rapid evolution of modern marine ecosystems in the Triassic where the same level of complexity as observed in today’s marine ecosystems is reached within 8 My after the Permian-Triassic mass extinction and within 4 My of the time reptiles first invaded the sea. This find also indicates that the biotic recovery in the marine realm may have occurred faster compared with terrestrial ecosystems, where the first apex predators may not have evolved before the Carnian.

Revisiting the Cranial Anatomy of the Thalattosaur Anshunsaurus huangnihensis

Cheng, L., Chen, X., Zhang, B., and Y. Cai. 2011. New Study of Anshunsaurus huangnihensis Cheng, 2007 (Reptilia: Thalattosauria): Revealing its Transitional Position in Askeptosauridae. Acta Geologica Sinica (English Edition) 85: 1231–1237. doi: 10.1111/j.1755-6724.2011.00584.x

Abstract - The skull of Anshunsaurus huangnihensis Cheng, 2007, especially the skull roof, is described in detail in this paper. Compared to other genera and species of Askeptosauroidea, Anshunsaurus huangnihensis has some important transitional characters from Askeptosaurus italicus to Anshunsaurus huangguoshuensis: the rostral length related to the skull length between Askeptosaurus italicus and Anshunsaurus huangguoshuensis; the postfrontal existing but distinctly reduced; the posterolateral process relatedly short and overlapping the parietal. The phylogenetic analysis weakly supports the evolutional progress from Anshunsaurus huangnihensis to Anshunsaurus huangguoshuensis. The skeletal ratios indicated that the node among the Askeptosauridae ingroup. The evolutional direction of Askeptosauridae should be from Askeptosaurus italicus to Anshunsaurus huangguoshuensis. The skeletal ratios indicated that the evolutional progress is Askeptosaurus italicus -- Anshunsaurus huangnihensis -- Anshunsaurus huangguoshuensis. In biogeography provinces, the Askeptosauroidea taxa from south China have a close relationship with those from western Tethys; however, Xinpusaurus from the Late Triassic is more related to those from the eastern Pacific.