The pachypleurosaurid Dactylosaurus schroederi (Diapsida: Sauropterygia)

Abstract

Redescription of the small pachypleurosaurid nothosaur Dactylosaurus schroederi Nopsca, 1928, from the Muschelkalk of Upper Silesia (Gorny Slask), Poland, indicates that it closely resembles Neusticosaurus but differs from the latter in a number of features. The forelimb, especially the antebrachium, is very gracile. Dactylosaurus achieves a high degree of ossification at a much smaller body size than other Pachypleurosauridae. The pattern of interzygapophyseal articulation in the trunk region suggests that lateral flexion was largely suppressed. The Pachypleurosauridae represent a distinct radiation of Triassic sauropterygians and combine certain resemblances to plesiosaurs with a number of plesiomorphous features.