A basal ichthyosauriform with a short snout from the Lower Triassic of China.
The incompleteness of the fossil record obscures the origin of many of the more derived clades of vertebrates. One such group is the Ichthyopterygia, a clade of obligatory marine reptiles that appeared in the Early Triassic epoch, without any known intermediates. Here we describe a basal ichthyosauriform from the upper Lower Triassic (about 248 million years ago) of China, whose primitive skeleton indicates possible amphibious habits. It is smaller than ichthyopterygians and had unusually large flippers that probably allowed limited terrestrial locomotion. It also retained characteristics of terrestrial diapsid reptiles, including a short snout and body trunk. Unlike more-derived ichthyosauriforms, it was probably a suction feeder. The new species supports the sister-group relationships between ichthyosauriforms and Hupehsuchia, the two forming the Ichthyosauromorpha. Basal ichthyosauromorphs are known exclusively from south China, suggesting that the clade originated in the region, which formed a warm and humid tropical archipelago in the Early Triassic. The oldest unequivocal record of a sauropterygian is also from the same stratigraphic unit of the region.
Department of Earth and Planetary Sciences, University of California, Davis, One Shields Avenue, Davis, California 95616, USA.
Ryosuke
R
Motani
1] Laboratory of Orogenic Belt and Crustal Evolution, Ministry of Education, and Department of Geology and Geological Museum, Peking University, Yiheyuan Street 5, Beijing 100871, China [2] State Key Laboratory of Palaeobiology and Stratigraphy (Nanjing Institute of Geology and Palaeontology, Chinese Academy of Science), Nanjing 210008, China.
Da-Yong
DY
Jiang
Department of Research, Anhui Geological Museum, Jiahe Road 999, Hefei, Anhui 230031, China.
Guan-Bao
GB
Chen
Dipartimento di Scienze della Terra, Università degli Studi di Milano, Via Mangiagalli, 34-20133 Milan, Italy.
Andrea
A
Tintori
Center of Integrative Research, The Field Museum, Chicago, Illinois 60605-2496, USA.
Olivier
O
Rieppel
Key Laboratory of Economic Stratigraphy and Palaeogeography, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, 39 East Beijing Road, Nanjing 210008, China.
Cheng
C
Ji
Department of Research, Anhui Geological Museum, Jiahe Road 999, Hefei, Anhui 230031, China.
Jian-Dong
JD
Huang
D000825:Animal Structures / Q000033:anatomy & histology*; D000818:Animals; D002681:China; D005580:Fossils; D010802:Phylogeny; D012104:Reptiles / Q000033:anatomy & histology* / Q000145:classification*; D012886:Skull / Q000033:anatomy & histology