Pterodactylus? micronyx? CM 11426 (no. 44 in the Wellnhofer 1970 catalog), Late Jurassic ~150mya, was considered by Wellnhofer (1970) to be the largest specimen of Pterodactylus micronyx. It was distinguished by very slender and elongated metacarpal bones, which were much longer than the radius and subequal to manual 4.1. Here those differences separate CM 11 426 (no. 44) as a distinct genus derived from a sister to Beipiaopterus and a phylogenetic predecessor to BSPG 1911 I 31 (no. 42 in the Wellnhofer 1970 catalog), and Sos 2428 (mistakenly attributed to Pterodactylus longicollum.)
Distinct from TM 10341, the skull of no. 44 had a flattened rostrum and a dorsally concave profile. The naris and antorbital fenestra were smaller. The cranium extended further posteriorly and had a rounder profile. The jugal dipped posteriorly. The quadrate articulation was below mid-orbit.
Overall much smaller than and distinct from Beipiaopterus, the dorsal neural spines were taller and the sacrals were nearly as long as the dorsals.
The sternual complex was longer than half the humerus. The coracoid was much shorter than the scapula. The humerus was straighter with a smaller deltopectoral crest. The radius and ulna were more gracile. The proximal carpal was smaller. The metacarpus was much longer, a quarter longer than the radius. Fingers I-III were much shorter with smaller unguals. Manual 4.1 extended only to the carpus, but manual 4.2 was relatively longer, maintaining its proximity to the elbow. The wing tip was barely taller than the shoulder when folded and quadrupedal.
The ilium was longer, especially the posterior portion. No fenestra perforated the ischium. The prepubis posterior process was shorter. The hind limb was much longer and more gracile. The pes was relatively smaller but more robust with progressively shorter lateral digits. Digit II was clearly the longest. The phalanges within digit IV were subequal with m4.1 much shorter. Pedal 5.1 extended nearly as far as metatarsal IV.
N0. 44 is also notable for soft tissue preservation. The wing does not extend to the ankles (contra Elgin, Hone and Frey 2011), but extends to the elbow and thereafter the anterior femur, as in all other pterosaurs.
Once again a smaller pterosaur appears at the base of a new clade. This clade gave rise to the first flightless pterosaurs, including Sos 2428. Sos 2179 could well have been flightless also, but all that is known at present is the skull. The sister clade was the Azhdarchidae, which included Quetzalcoatlus, one of the largest known pterosaurs.
Distinct from the holotype of Pterodactylus (no. 4 in the Wellnhofer 1970 catalog), no. 44 had a concave rostral profile, more and smaller teeth, longer metacarpals, shorter fingers and a smaller foot with distinct plangeal proportions, among many other distinctions. These characters nest no. 44 far from the Pterodactylus clade.
See the pterosaur family tree here. |
