Thalattosuchians

Thalattosuchians are an under-rated clade of mesozoic animals. Part of Pseudosuchia, the crocodile-like archosaurs, they were completely adapted to a marine lifestyle.

Mesozoic oceans must have been terrifying places. Thalattosuchians, ichthyosaurs, plesiosaurs, mosasaurs, and gigantic ammonoids seem like they were all common, although maybe not all at the same time and place.

Here’s a convenient overview of thalattosuchians.

A recent paper about their skin, which was smooth, unlike modern day crocodiles/alligators/gharials/caimans. Thalattosuchians also seem to have had tail flukes, and sclerotic rings in their eyes. Mosasaurs had them. Modern crocodiles and alligators do not have sclerotic rings. The rings’ presence may indicate rapid underwater movement.

I attribute public ignorance of thalattosuchians, and indeed, all Pseudosuchians like aetiosaurs, to the fact that no Pseudosuchian was included in the Marx plastic dinosaurs that were common in the early 1960s. You can see the echoes of these plastic dinosaurs today, in kids books like How do dinosaurs say good night?, which includes a Dimetrodon and a Trachodon. Dimetrodons were early Permian synapsids, not dinosaurs at all, while Trachodon seems to have resulted from a mis-interpretation of two different kinds of dinosaur teeth. In any case, Marx missed a bunch of really cool animals.

A fully articulated thalattosuchian skeleton

For a wider ranging discussion of crocodylomorph disparity, including a little bit about thalattosuchians, there’s a Palaeocast episode

PBS Eons did a video on metriorhynchids, the most aquatic adapted thalattosuchians that’s well worth watching. Eons also did a video on Triassic Pseudosuchia that will help inform you.

Attribution of life reconstruction image above

I’m supposed to attribute the reconstruction above like this:

By Mark T. Young, Stephen L. Brusatte, Marco Brandalise de Andrade, Julia B. Desojo, Brian L. Beatty, Lorna Steel, Marta S. Fernández, Manabu Sakamoto, Jose Ignacio Ruiz-Omeñaca, Rainer R. Schoch. - Young, Mark T. Brusatte, Stephen L.; De Andrade, Marco Brandalise; Desojo, Julia B.; Beatty, Brian L.; Steel, Lorna; Fernández, Marta S. Sakamoto, Manabu; Ruiz-Omeñaca, José Ignacio; Schoch, Rainer R ; (2012) "The Cranial Osteology and Feeding Ecology of the Metriorhynchid Crocodylomorph Genera Dakosaurus and Plesiosuchus from the Late Jurassic of Europe", in Butler, Richard J. (ed.), PLoS ONE, vol. 7, no. 9, p. e44985, pmid 23028723, pmc 3445579, doi:10.1371/journal.pone.0044985, CC BY 2.5, https://commons.wikimedia.org/w/index.php?curid=35907223