. Breviora. . Figure 12. The left calcaneum of Erythrosuchus in A) ventral, and B) distal views; and Chasmatosaurus in C) ventral, and D) distal views. Erythrosuchus drawing based on cast of Bernard Price Institute F. 2069 M 405, Chasmatosaurus drawing based on cast of NM C 3016, Nasionale Museum, Bloemfontein. although Cruickshank (1978) identifies a perforating foramen, a primitive feature that is also present in Chasmatosaurus. Thus the tarsus of Erythrosuchus is best considered a poorly ossified proterosuchian tarsus. A reduction of ossification is commonly seen in aquatic animals, and pro
. Breviora. . Figure 12. The left calcaneum of Erythrosuchus in A) ventral, and B) distal views; and Chasmatosaurus in C) ventral, and D) distal views. Erythrosuchus drawing based on cast of Bernard Price Institute F. 2069 M 405, Chasmatosaurus drawing based on cast of NM C 3016, Nasionale Museum, Bloemfontein. although Cruickshank (1978) identifies a perforating foramen, a primitive feature that is also present in Chasmatosaurus. Thus the tarsus of Erythrosuchus is best considered a poorly ossified proterosuchian tarsus. A reduction of ossification is commonly seen in aquatic animals, and probably reflects an adaptation for an aquatic habitat, rather than the development of a mechanically distinct structural complex. A fully terrestrial erythro- suchid would, therefore, be expected to have a tarsus like that of Chasmatosaurus. Since this kind of tarsus is the structural ancestor of the crocodile-normal tarsus, the structure of the erythrosuchid tarsus neither supports nor negates a relationship between erythro- suchids and rauisuchids. If a relationship between erythrosuchids and rauisuchids is accepted on the basis of similarities in the skull, it is necessary to assume that the crocodile-normal tarsus originated after the origin of this radiation of thecodonts, and therefore the tarsus cannot be used as the defining feature of the Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Harvard University. Museum of Comparative Zoology. Cambridge, Mass. , Museum of Comparative Zoology, Harvard University
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