A new specimen of Hupehsuchus nanchangensis Young, 1972 (Diapsida, Hupehsuchia) from the Triassic of Hubei, China

et al. 2019

PeerJ

A new species of ichthyosauriform is recognized based on 20 specimens, including nearly complete skeletons, and named Chaohusaurus brevifemoralis. A part of the specimens was previously identified as Chaohusaurus chaoxianensis and is herein reassigned to the new species. The new species differs from existing species of Chaohusaurus in a suite of features, such as the bifurcation of the caudal peak neural spine and a short femur relative to trunk length. The specimens include both complete and partially disarticulated skulls, allowing rigorous scrutiny of cranial sutures. For example, the squamosal does not participate in the margin of the upper temporal fenestra despite previous interpretations. Also, the frontal unequivocally forms a part of the anterior margin of the upper temporal fenestra, forming the most medial part of the anterior terrace. The skull of the holotype largely retains three-dimensionality with the scleral rings approximately in situ, revealing that the eyeball was uncovered in two different directions, that is, laterally and slightly dorsally through the main part of the orbit, and dorsally through the medial extension of the orbit into the skull roof. This skull construction is likely a basal feature of Ichthyosauromorpha. Phylogenetic analyses place the new species as a sister taxon of Chaohusaurus chaoxianensis.

Section: Resultsmentioning

confidence: 86%

Section: Discussionmentioning

confidence: 99%

The new ichthyosauriformChaohusaurus brevifemoralis(Reptilia, Ichthyosauromorpha) from Majiashan, Chaohu, Anhui Province, China

Huang

Motani

et al. 2019

PeerJ

“…The ribs are curved in their proximal and middle parts, but their distal parts are straight. All the ribs are single-headed, and each rib head would have articulated with the synapophysis formed by the centrum and neural arch of the corresponding vertebra, similar to many other early ichthyosauromorphs and to early sauropterygians ( Jiang et al, 2014 ; Cheng et al, 2016 ; Jiang et al, 2016 ; Wu et al, 2016 ; Huang et al, 2019 ; Li & Liu, 2020 ). In Utatsusaurus , by contrast, some of the ribs are double-headed ( Shikama, Kamei & Murata, 1978 ).…”

Section: Resultsmentioning

confidence: 91%

“…The neural arches contribute significantly to the articular facets as in Chaohusaurus ( Huang et al, 2019 ), but unlike the condition in Omphalosaurus ( Sander & Faber, 2003 ). In hupehsuchians, the diapophyses of the neural arches also contribute to synapophyseal facets, but the facets are positioned more posteriorly than Baisesaurus ( Chen et al, 2014b , 2015 ; Wu et al, 2016 ). The prezygapophysis is well preserved in the 7th neural arch, and separated from the corresponding diapophysis by a smooth, concave surface ( Fig.…”

Section: Resultsmentioning

confidence: 99%

A new basal ichthyosauromorph from the Lower Triassic (Olenekian) of Zhebao, Guangxi Autonomous Region, South China

Ren

Xiang

et al. 2022

PeerJ

Here we describe a newly discovered basal ichthyosauromorph from the Lower Triassic of South China, Baisesaurus robustus gen. et sp. nov. The only known specimen of this new species was collected from the Lower Triassic (Olenekian) Luolou Formation in the Zhebao region of Baise City, on the northwest margin of the Nanpanjiang Basin, and comprises a partial skeleton including the ribs, the gastralia, a limb element, 12 centra, and seven neural arches. Comparisons to a wide variety of Early Triassic marine reptiles show Baisesaurus robustus to be a basal ichthyosauromorph based on the following features: neural arches lack transverse processes; dorsal ribs are slender, and not pachyostotic even proximally; and median gastral elements have long, sharp anterior processes. The limb element is long and robust, and is most likely to be a radius. Baisesaurus robustus is large (estimated length more than 3 m) relative to early ichthyosauromorphs previously discovered in China, and shares noteworthy morphological similarities with Utatsusaurus hataii, particularly with regard to body size and the morphology of the probable radius. Baisesaurus robustus also represents the first record of an Early Triassic ichthyosauromorph from Guangxi Autonomous Region, extending the known geographic distribution of ichthyosauromorphs in South China.

“…Hupehsuchia has been known since 1959 11 but remained poorly understood until the recent rush of discoveries made by the Wuhan Centre of China Geological Survey (WGSC) 5 , 12 – 15 (see also 16 ). Hupehsuchia are now noted for their high taxonomic diversity despite their narrow temporal and geographical ranges 15 .…”

Section: Introductionmentioning

confidence: 99%

Early Triassic marine reptile representing the oldest record of unusually small eyes in reptiles indicating non-visual prey detection

Cheng

Motani

et al. 2019

Sci Rep

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.