A generic revision of the Protolabidini (Mammalia, Camelidae) with a description of two new protolabidines. Bulletin of the AMNH ; v. 161, article 3
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Date
1978
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New York : American Museum of Natural History
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Abstract
"A revised diagnosis of the Protolabidini characterizes the tribe as having a narrow rostrum and laterally expanded anterior nares. Tanymykter, new genus, possess the above derived features and is included in the Protolabidini as the primitive sister taxon to Protolabis. The morphological features that separate Tanymykter from Protolabis are all primitive except for the derived condition of closely appressed P[superscript]1[subscript]1 roots. Based upon new material from the Milk Creek Formation, morphological distinctions between Protolabis and Procamelus are clarified. The principal derived features of Protolabis coartatus that differ from Procamelus are extreme constriction of the rostrum, lateral expansion of the anterior nares, P[subscript]1 and P[subscript]2 small and sometimes absent, and a mandibular angle with extreme lateral flare and a prominent mesial tuberosity. Although the above derived features are less pronounced, they are still present in Protolabis heterodontus and other undescribed samples in the collection of the American Museum of Natural History. Thus, Stirton's species, coartatus, which has previously confused the generic concept of Procamelus, is transferred to Protolabis. The small size of the cranium and coronoid process is correlated with the strong lateral and mesial flare of the mandibular angle in P. coartatus. This reflects increased emphasis on the masseter and pterygoid muscles in mastication and less emphasis on the temporalis. In contrast, the large coronoid process in Procamelus indicates greater emphasis on the temporalis muscle. Oxydactylus exilis Matthew is transferred to Michenia because it shares the derived features of a narrow rostrum, incisiform upper canine, and a shallow symphysis. A new species, Michenia yavapaiensis, with P[subscript]1 unerupted, P[subscript]2 small, unerupted or absent, and tall-crowned molars is described from the Milk Creek Formation. Finally, a cladogram of proposed relationships of the Protolabidini is presented, including Tanymykter, new genus, Protolabis and Michenia with supporting evidence for this tribe being a monophyletic group. The relationship of other members of the Camelinae to the Protolabidini is also discussed. A short section detailing the stratigraphic framework of the Milk Creek Formation, Yavapai County, Arizona is included"--P. 371.
Description
p. 369-425 : ill. ; 26 cm.
Includes bibliographical references (p. 423-425).
Includes bibliographical references (p. 423-425).
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