La Boca Formation Animals

[DD1991]

All of may not know this, but the Middle Jurassic La Boca Formation in Mexico boasts the most important Middle Jurassic tetrapod fauna in North America outside the US. Among the notable fossils found in the La Boca Formation are primitive mammals, sphenodonts, and even archosaurs (incl. the pterosaur "Dimorphodon" weintraubi and an unnamed mesoeucrocodylian). When compared to other Middle Jurassic faunas, it's interesting that the tritylodont Bocatherium is roughly the same age as the other two Middle Jurassic tritylodonts Bienotheroides and Stereognathus. As some of the components of the La Boca Formation vertebrate assemblage are related to their counterparts in China and Europe (e.g Bocatherium), future discoveries in the La Boca Formation could provide a new window into the biogeographic origin of the Morrison fauna, and it's not implausible that the Morrison fauna may have originated in Patagonia.

Clark, James; Montellano, Marisol; Hopson, James A., Hernandez, Rene; & Fastovsky, David A. (1994). "An Early or Middle Jurassic tetrapod assemblage from the La Boca Formation, northeastern Mexico". In Fraser, N.C.; and Sues, H.-D. (Eds.). In The Shadow of the Dinosaurs: Early Mesozoic Tetrapods. Cambridge: Cambridge University Press. pp. 295–302.

[Regg Cato]

Interesting concept; the middle Jurassic of North America is still such a big gap to be filled (at least as far as dinosaurs are concerned).