Browsing by Author "Baird, Donald."
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Item The Carboniferous amphibian Tuditanus (Eosauravus) and the distinction between microsaurs and reptiles. American Museum novitates ; no. 2337(New York, N.Y. : American Museum of Natural History, 1968) Carroll, Robert Lynn, 1938-; Baird, Donald."The genus Tuditanus (Eosauravus) from the Middle Pennsylvanian of Linton, Ohio, is redescribed on the basis of the two type specimens, neither of which had previously been prepared. This animal, which has been considered alternatively a microsaurian amphibian and a primitive reptile, proves to be a microsaur having these characteristics: sculptured skull roof with orbits lying at mid-length and palpebral cups; about 25 isodont marginal teeth; postparietals occipital in position; 29 presacral vertebrae; ilium with dorsal and posterior processes; stout limbs with entepicondylar foramen in humerus; tetradactyl manus with phalangeal count of 2, 3, 4, 3; pentadactyl pes with astragalus and calcaneum and a phalangeal count of 2, 3, 4, 5, 4; and hoe-shaped ungual phalanges. Tuditanus is clearly a member of the central group of microsaurs, although it shows a number of terrestrial adaptations similar to those observed in captorhinomorph reptiles. The anatomy of all microsaur genera is reviewed in order to determine whether any members of this group might be related to the ancestry of reptiles. The following features are found to be characteristic of all microsaurs, and to distinguish them from reptiles: (1) the presence of no more than a single bone in the temporal series; (2) the absence of a transverse flange from the pterygoid; (3) the concave occipital condyle articulating with a single specialized cervical vertebra; (4) the absence of trunk intercentra; and (5) the oval dorsal scales with radial striations superimposed on a concentric growth pattern. These features indicate that microsaurs could share a common ancestry with reptiles only at, or near, the level of the rhipidistian fish and only in pre-Carboniferous time"--P. 46-47.Item Coelurosaur bone casts from the Connecticut Valley Triassic. American Museum novitates ; no. 1901(New York, N.Y. : American Museum of Natural History, 1958) Colbert, Edwin Harris, 1905-; Baird, Donald.; New England Museum of Natural History.Item Studies on Carboniferous freshwater fishes. American Museum novitates ; no. 2641(New York, N.Y. : American Museum of Natural History, 1978) Baird, Donald."New material from Nova Scotia, Illinois, and Pennsylvania casts light on certain fish taxa and faunas found in freshwater deposits of the Pennsylvanian and latest Mississippian. The earliest representative of the palaeoniscoid family Haplolepidae is described as Haplolepis (Parahaplolepis) canadensis, a new species distinguished from H. tuberculata by the shape of its frontals and from H. anglica by their tuberculate structure. The presence of H. (P.) canadensis in the early Pennsylvanian (Westphalian A) of Nova Scotia implies a separation of the subgenus Parahaplolepis from the basal haplolepid stock in Mississippian time. The lungfish genus Ctenodus, hitherto extremely rare in North America, is in fact represented by its three European species, each in strata of appropriate age: the primitive C. interruptus in the latest Mississippian (Namurian A) of Nova Scotia, the intermediate C. cristatus in the middle Pennsylvanian (early Westphalian D) of Illinois, and the specialized C. murchisoni in the late Westphalian D of Nova Scotia. Ctenodus, Conchopoma, and Megapleuron constitute a highly anomalous lungfish assemblage in the Mazon Creek deposits of Illinois. Pennsylvanian records of the acanthodian genus Gyracanthus in the Western Hemisphere, previously limited to two specimens, can now be extended by Nova Scotian finds dating from the Namurian A and Westphalian A and B. An unexpectedly late survival of Gyracanthus into Westphalian D time is documented by spines from Illinois; Trichorhipis praecursor is reinterpreted as a prepectoral spine of Gyracanthus. The previously unreported fish fauna of the classic locality at Cannelton, Pennsylvania, comprises the coelacanth Rhabdoderma elegans, the crossopterygian Rhizodopsis cf. robustus, the palaeoniscoids Haplolepis aff. ovoidea and Elonichthys peltigerus and a third genus resembling Commentrya, and the sharks Xenacanthus compressus and Bandringa rayi. The latter genus is shown to be a ctenacanthoid derivable from Goodrichthys, and of freshwater rather than marine habitat"--P. [1].