The reorganization of the ankle in basal amniotes has long been considered a key
innovation allowing the evolution of more terrestrial and cursorial behavior. Understanding …

The origin of the amniote astragalus, the enlarged proximal tarsal distal to the tibia and one
of the few diagnostic skeletal features of the group (Carroll, 1970; Gauthier et al., 1988), has …

The homology and evolution of the archosaur ankle is a controversial topic that has been
deeply studied using evidence from both extinct and extant taxa. In early stem archosaurs …

In extant turtles and lepidosaurs, the astragalus forms from a single ossification center in a
tarsale proximale resulting from fusion of originally separate chondrogenic condensations in …

Caenagnathid elements are exceptionally rare in the Horseshoe Canyon Formation (HCF),
and a small tibia constitutes only the fourth record from the formation. The tibia is elongate …

The anklebone (astragalus) of dinosaurs presents a characteristic upward projection, the
'ascending process'(ASC). The ASC is present in modern birds, but develops a separate …

The hypotheses about the origin of the primitive amniotic tarsus are very speculative. Early
studies argued that the origin of the astragalus, one of the largest proximal bones in the …

ABSTRACT A well-preserved astragalus of the anomaluroid rodent Pondaungimys
anomaluropsis is described from the late middle Eocene Pondaung Formation of central …

Two different patterns of the condensation and chondrification of the limbs of tetrapods are
known from extensive studies on their early skeletal development. These are on the one …

Abstract The Lower Triassic amphibians Triadobatrachus massinoti and Czatkobatrachus
polonicus are universally regarded as stem anurans. However, there is still uncertainty …