Pentadactyl manus of the Metoposaurus krasiejowensis from the Late Triassic of Poland, the first record of pentadactyly among Temnospondyli. Issue 6 (24th July 2020)

• Record Type: Journal Article
• Authors: Konietzko‐Meier, Dorota; Teschner, Elżbieta M.; Bodzioch, Adam; Sander, P. Martin
• Is Part Of: Journal of anatomy. Volume 237:Issue 6(2020)
• Page Start: 1151
• Page End: 1161
• Publication Date: 2020-07-24
• Subjects: digits -- manus -- Metoposaurus -- ossification -- Temnospondyli; Anatomy -- Periodicals; 571.3
• DOI: 10.1111/joa.13276
• Languages: English
• ISSNs: 0021-8782

Abstract

Abstract: Temnospondyli are commonly believed to have possessed four digits in the manus and five in the pes. However, actual finds of articulated autopodia are extremely rare. Therefore, an articulated, slightly incomplete forelimb skeleton with preserved manus of Metoposaurus krasiejowensis from the Late Triassic of Poland is important in providing new details about the structure and ossification sequence in the temnospondyl limb. The most important observation is the presence of five metacarpals in this specimen. This allows reconstructing the manus as pentadactyl. The number of phalanges and the distribution of distal articulation facets allow reconstruction of the digit formula as (2?)‐3‐3‐(3?)‐(2?). The well‐developed fifth digit suggests that the Metoposaurus manus shows a unique ossification sequence: the reduction or late ossification of the first digit conforms to the amniote‐frog pattern, and the early development of the second and third digit makes M etoposaurus similar to salamanders. Based on the distribution of pentadactyly vs. tetradactyly in the temnospondyl manus, the number of digits was not phylogenetically constrained in temnospondyls, similar to today's amphibians. Abstract : Metoposaurus krasiejowensis from the Late Triassic of Poland shows a unique for Temnospondyli structure of the manus with five digits. Based on the distribution of pentadactyly vs. tetradactyly in the temnospondyl manus, the number of digits was not phylogenetically constrained in temnospondyls, similar to today's amphibians.