Thalattosuchia is a clade of mostly marine crocodylomorphs from the Early Jurassic to the Early Cretaceous that had a cosmopolitan distribution.[3] They are colloquially referred to as marine crocodiles or sea crocodiles, though they are not members of Crocodilia and records from Thailand and China suggest that some members lived in freshwater.[4] The clade contains two major subgroupings, the Teleosauroidea and Metriorhynchoidea. Teleosauroids are not greatly specialised for oceanic life, with back osteoderms similar to other crocodyliformes. Within Metriorhynchoidea, the Metriorhynchidae displayed extreme adaptions for life in the open ocean, including the transformation of limbs into flippers, the development of a tail fluke, and smooth, scaleless skin,[5] and probably gave live birth, seemingly uniquely among archosaurs.[6]
Indeterminate remains possibly belonging to thalattosuchians have been reported from the Early Jurassic (Sinemurian) of Chile and France. However, they cannot be assigned to the group with confidence as they lack diagnostic characters.[9] In 2023 a basal teleosauroid was reported from the earliest Jurassic (Hettangian-Sinemurian) of Morocco, representing one of the oldest known thalattosuchians.[10]Turnersuchus from the Pliensbachian of England appears to be basal to both Teleosauroidea and Metriorhynchoidea.[9] While abundant during the Jurassic, their fossil record during the Early Cretaceous is scarce, and generally confined to low latitudes. The latest records of the group date to the Aptian.[11][12] Some members of Teleosauridae have been discovered in non-marine deposits.[4]
^ abFraas E. 1901. Die Meerkrokodile (Thalattosuchia n. g.) eine neue Sauriergruppe der Juraformation. Jahreshefte des Vereins für vaterländische Naturkunde, Württemberg57: 409-418.
^Alfio A. Chiarenza; Davide Foffa; Mark T. Young; Gianni Insacco; Andrea Cau; Giorgio Carnevale; Rita Catanzariti (2015). "The youngest record of metriorhynchid crocodylomorphs, with implications for the extinction of Thalattosuchia". Cretaceous Research. 56: 608–616. Bibcode:2015CrRes..56..608C. doi:10.1016/j.cretres.2015.07.001. hdl:2318/1537833.
^Chiarenza, Alfio A.; Foffa, Davide; Young, Mark T.; Insacco, Gianni; Cau, Andrea; Carnevale, Giorgio; Catanzariti, Rita (September 2015). "The youngest record of metriorhynchid crocodylomorphs, with implications for the extinction of Thalattosuchia". Cretaceous Research. 56: 608–616. Bibcode:2015CrRes..56..608C. doi:10.1016/j.cretres.2015.07.001. hdl:2318/1537833.
Further reading
Fraas, E. (1902). "Die Meer-Krocodilier (Thalattosuchia) des oberen Jura unter specieller Berücksichtigung von Dacosaurus und Geosaurus". Paleontographica49: 1-72.