#thoracopterid

[wtf-triassic]

Thoracopterus

By @evolution-incarnate

Etymology: Chest wings

First Described By: Bronn, 1858

Classification: Biota, Archaea, Proteoarchaeota, Asgardarchaeota, Eukaryota, Neokaryota, Scotokaryota, Opimoda, Podiata, Amorphea, Obazoa, Opisthokonta, Holozoa, Filozoa, Choanozoa, Animalia, Eumetazoa, Parahoxozoa, Bilateria, Nephrozoa, Deuterostomia, Chordata, Olfactores, Vertebrata, Craniata, Gnathostomata, Eugnathostomata, Osteichthyes, Actinopterygii, Peltopleuriformes, Thoracopteridae

Referred Species: T. niederristi, T. magnificus, T. martinsi, T. wushaensis

Status: Extinct 

Time and Place: 242 to 209 Ma, from the Ladinian of the Middle Triassic to the Norian of the Late Triassic.

Thoracopterus is known from Italy, Austria, and China.

Physical Description: Thoracopterus is one of the earliest known flying fish. Not a flying fish as in the modern group of flying fish (Exocoetidae), but a fish that flies. Thoracopterus’s pectoral and pelvic fins were greatly expanded into wings. The pectoral wings were almost as long as the rest of the fish! These would have given these fish the ability to glide over the water surface. Besides the wings, Thoracopterus would have looked like an unremarkable fish. Its head was short-snouted and had large eyes, its dorsal fin was placed very far back on the body, and the lower lobe of the caudal fin was longer than the upper one.

Diet: Thoracopterus likely fed on smaller animals, which given how large it was (10 cm at most), would have probably been mostly plankton.

Behavior: It is presumed that thoracopterid behavior was very similar to those of modern flying fish. When threatened by predators, Thoracopterus would likely swim particularly fast to break free from the water surface. When in the air, it would fan out its fins to glide in the air for a considerable distance (modern flying fish can glide for up to 45 seconds), hopefully evading the predator. Jumping is also used during spawning displays in modern flying fish, so this may have also been the case for Thoracopterus. As a small pelagic fish, Thoracopterus likely lived in schools - small pelagic fish tend to do that, because that reduces the chance each individual has of being eaten.

Ecosystem: Thoracopterus fossils are found in Europe and China, which… is the case for a lot of Triassic marine animals, actually. Each environment was pelagic, but probably not too far out from the shore. In Europe, Thoracopterus lived alongside a variety of other fish, such as Belonorhynchus, Saurichthys, Graphiurichthys, Paralepidotus, Peltopleurus, and Pholidopleurus, as well as decapod crustaceans. In China, Thoracopterus lived alongside ammonites like Ptychites and Detoniceras and early marine reptiles, such as the thalattosaur Xinpusaurus and the nothosaur Keichousaurus.

Other: The taxonomy of thoracopterids is a bit of a mess. Phylogenetic analysis suggests that T. martinsi, T. magnificus and T. wushaensis may be more closely related to Gigantopterus and Potanichthys than to the type species of Thoracopterus, T. niederristi. However, it has also been suggested that Potanichthys is the same species as the earlier-named T. wushaensis, so then that becomes Thoracopterus and only Gigantopterus stands out. Or you could lump them all, including Gigantopterus, into Thoracopterus. It really depends on where you set your genericometer. For the purposes of this article, I have described Thoracopterus sensu lato.

~ By Henry Thomas

Sources under the cut

BBC 2008. Fast flying fish glides by ferry. http://news.bbc.co.uk/2/hi/science/nature/7410421.stm

Tintori, A., Sassi, D. 1992. Thoracopterus Bronn (Osteichthyes: Actinopterygii):  A gliding fish from the Upper Triassic of Europe. Journal of Vertebrate Paleontology 12(3): 265-283.

Tintori, A., Hitij, T., Jiang, D., Lombardo, C., Sun, Z. 2013. Triassic actinopterygian fishes: the recovery after the end-Permian crisis. Integrative Zoology 9(4): 394-411.

Tintori, A. 2015. Setting the record straight for fossil flying fishes versus non-flying ones: a comment on Xu et al. (2015). Biology Letters 11(11).

Xu, G., Zhao, L., Gao, K., Wu, F. 2013. A new stem-neopterygian fish from the Middle Triassic of China shows the earliest over-water gliding strategy of the vertebrates. Proceedings of the Royal Society B 280: 20122261.

Xu, G., Zhao, L., Shen, C. 2015. A Middle Triassic thoracopterid from China highlights the evolutionary origin of overwater gliding in early ray-finned fishes. Biology Letters 11(1).

#thoracopterus #thoracopterid #fish #triassic #triassic madness #triassic march madness #prehistoric life #paleontology