sexta-feira, 26 de dezembro de 2014
Triassic Seas of South China
Keichousaur-killer of Xingyi
Acrylics, digital and photography, 2013
2nd in a series for the following review paper =
Michael J. Benton, Qiyue Zhang, Shixue Hu, Zhong-Qiang Chen, Wen Wen, Jun Liu, Jinyuang Huang, Changyong Zhou, Tao Xie, Jinnan Tong & Brian Choo (accepted manuscript), Exceptional vertebrate biotas from the Triassic of China, and the expansion of marine ecosystems after the Permo-Triassic mass extinction, Earth Science Review. [link]
ca. 235,000,000 bp, uppermost Middle Triassic (late Ladinian), Xingyi County, Guizhou, China (Zhuganpo Formation).
A coastal reef at the very end of the Middle Triassic. We're close to the shores of a large island, over 100 km off the South Chinese mainland. Sleek and deadly, a nothosaur snacks on it's abundant smaller relatives, the keichousaurs, ducking beneath the incredible neck of Tanystropheus to do so. Other reef denizens flee in terror while ammonoids and wing-finned Potanichthys hover unconcerned in the surface waters.
Nothosaurus youngi - (big yellowish foreground predator) 2.1m long. Nothosaurs were the most badass predators of the Triassic seas. N. youngi was one of the smaller members of it's genus but still formidably armed with wicked-looking teeth.
Keichousaurus hui - (numerous small reptiles in foreground) Under 30cm. by far the most abundant tetrapod in the Xingyi biota, known from hundreds, if not thousands, of specimens ranging from embryoes to adults.
Yunguisaurus liae - (pair of long-necked swimmers in background) Up to 4.5m long. the Middle Triassic sauropterygians most completely adapted for aquatic life were pistosaurs like Yunguisaurus. Their long-necked, paddle-limbed body configuration was a winning formula that was taken to extremes by their plesiosaur descendants later in the Mesozoic.
Tanystropheus cf.longobardicus - (huge long-necked reptile stretching into foreground) 6m long, over half of which is neck. Remains of this preposterously long-necked protorosaur from Xingyi include an almost complete skeleton that is effectively indistinguishable from T. longobardicus from Italy and Switzerland - unfortunately the head is missing on the Chinese specimen so we can't be totally sure. A predator of cephalopods and small fish (based on gut contents of European specimens), the body of Tany shows no obvious adaptations for marine life. However it's pan-Tethyan distribution and presence at Xingyi, 100s of kms from the nearest continental landmass, suggest considerable maritime capabilities.
Anshunsaurus wushaensis - (serpentine reptile in background) 2.5m long thalattosaur with a small ichthyosaur-like head. At this time thalattosaurs were rare in the region and not very diverse, however the group was about to come into their own within a few million years.
The apparent absence of ichthyosaurs at Xingyi is puzzling...
Peltopleurus orientalis - 5cm, numerous small brown fishes.
Guizhoubrachysoma minor - 4cm, short, blue fishes.
Guizhouamia bellula - 15cm, slender fishes with orange stripes. Originally described as the world's oldest bowfin (amiid). It isn't.
Asialepidotus shigyiensis - 20cm, brown fishes with vertical bands. Guizhouella/Guizhoueugnathus analilepida is a synonym.
Potanichthys xingyiensis - 15cm, big-winged fishes near the surface. The most famous of the Xingyi fishes, Potanichthys was one of the first attempts at flight by the Actinopterygii with many convergent similarities in fin shape and body form to modern flying fishes.
Schimperella acanthocercus - 4cm minus antennae. numerous small shrimps. Yes, I think Japanese crystal red shrimps are cool. Probably the most common fossils at Xingyi.
Protrachyceras sp. - ammonoids.
Traumatocrinus hsui - floating colony of crinoids in the far distance. Rare at Xingyi, as with the thalattosaurs, these huge echinoderms would become far more common within a few million years.