Dimorphodon weintraubi and Mesadactylus

Dimorphdon? weintraubi (Clark et al. 1994) Early to Early Middle Jurassic, ~175 mya, ~40 cm snout-to-vent length [IGM 3494] was previously considered a species of Dimorphodon, in part due to its similar size, IGM 3494 was derived from a sister to the other large protoanurognathid, the IVPP embryo, and phylogenetically preceded Dendrorhynchoides, a basal anurognathid.

Distinct from the IVPP embryo, D. weintraubi had a much larger humerus. The remaining elements were more robust. Fingers 1-3 were much longer, similar in proportion to those of Peteinosaurus.

This uncrushed specimen helped Clark, et al. (1998) determine that the basal pterosaur pes was incapable of a digitigrade configuration because the flat metatarsophalangeal joints did not permit the sort of extension seen in birds. This is true. However, sufficient elevation of the posterior pes was permitted by the sort of extension seen in bipedal lizards, including Cosesaurus, of the interphalangeal joints (Peters 2000).

Sauria aberrante MLP 61-IX-4-1 Early Jurassic ~175 mya, (Casamiquela 1962) had a short digit I, and increasingly longer digits laterally. The proximal phalanges made impressions. The digits radiated with medially curving phalanges in which mt III was slightly longer than mt IV. The unguals were all very short. This Patagonian ichnite also most closely matches the pes of Dimorphodon? weintraubi (see above), the only other example of a protoanurognathid from the western hemisphere. Here is a bipedal, digitigrade basal pterosaur ichnite. As in Rotodactylus, digit V impressed far behind the others.

Dimorphodon weintraubi is featured in

Mesadactylus ornithosphyos (Jensen and Padian 1989, Late Jurassic) was considered a pterodactyloid, but here nests with the basal Anurognathidae. The fused sacrum and high neural arch are different than other anurognathids.

Casamiquela RM 1962. Sobre la pisada de un presunto sauria aberrante en el Liassico del Neuquen (Patagonia). Ameghiniana 2, 10:183-186.

Clark J, Montellano M, Hopson J and Fastovsky D. 1994. In: Fraser, N. & H.-D Sues, Eds. 1994. In the Shadows of Dinosaurs. New York, Cambridge: 295-302.

Clark J, Hopson J, Hernandez R, Fastovsk D and Montellano M. 1998. Foot posture in a primitive pterosaur. Nature 391:886-889.

Jenson J and Padian K 1989. Small pterosaurs and dinosaurs from the Uncompaghre fauna (Brushy Basin Member, Morrison Formation: ?Tithonian), Late Jurassic, western Colorado. Journal of Paleontology 63:364-373.

Peters D 2000. Description and Interpretation of Interphalangeal Lines in Tetrapods. - Ichnos 7(1): 11-41.

Pterosauria

Austriadactylus SC 332466

Austriadraco

Dimorphodontoidea

Preondactylus

Dimorphodon