Open AccessLoss of carpal elements in crocodilian limb evolution: morphogenetic model corroborated by palaeobiological data
Author(s) -
Buscalioni Angela D.,
Ortega Francisco,
RasskinGutman Diego,
PérezMoreno Bernardino P.
Publication year - 1997
Publication title -
biological journal of the linnean society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.906
H-Index - 112
eISSN - 1095-8312
pISSN - 0024-4066
DOI - 10.1111/j.1095-8312.1997.tb01618.x
Subject(s) - biology , crocodile , alligator , tetrapod (structure) , extant taxon , manus , american alligator , neoteny , myology , evolutionary biology , anatomy , deuterostome , soma , vertebrate , zoology , paleontology , biochemistry , neuroscience , gene
The comparison of bone homology between the manus of an Early Cretaceous fossil crocodile and that of the extant species Alligator mississippiensis supports explicidy, for the first time, the hypothesis of carpal loss in crocodilian limb evolution. This hypothesis, based on a developmental model of the organization of the tetrapod limb, is in accordance with the fossil evidence, and may supersede traditional Haeckelian views based on recapitulatory paradigms. The homologous relationships of carpal elements reveal the existence of two carpal patterns‐ one plesiomorphic and one apomorphic‐in the crocodilian lineage. Phylogenetic change is explained causally by alterations of the osteogenesis of the distal carpals 2 and 3, which remain unossified in extant crocodile adults. This implies that crocodilian limb evolution is constrained by a process of paedomorphosis. This modification of the architecture of the crocodilian hand is a terminal event of its evolutionary history, affecting only eusuchian crocodiles. The results of this study contest the traditional view that the skeletal pattern of the crocodilian limb has been conserved unchanged since the Triassic.