. Bonner zoologische Monographien. Zoology. 96. : Dorsolateral view of the left interorbital region (see inset) of Cystophora cristata (USNM 188914) illustrating selected characters (indicated by their number; see Character Analysis) of this region. Anterior is towards the right of the page and dorsal to the top, with the zygomatic arch framing the bottom of the illustration. Abbreviations are as follows: FR = frontal; MAX = maxilla; OR = orbitosphenoid; PAL = palatine; PAR = parietal; and SQ = squamosal. Scale bar equals 1 cm. Inset adapted from Lawlor (1979). Among pinnipeds, the gener
. Bonner zoologische Monographien. Zoology. 96. : Dorsolateral view of the left interorbital region (see inset) of Cystophora cristata (USNM 188914) illustrating selected characters (indicated by their number; see Character Analysis) of this region. Anterior is towards the right of the page and dorsal to the top, with the zygomatic arch framing the bottom of the illustration. Abbreviations are as follows: FR = frontal; MAX = maxilla; OR = orbitosphenoid; PAL = palatine; PAR = parietal; and SQ = squamosal. Scale bar equals 1 cm. Inset adapted from Lawlor (1979). Among pinnipeds, the general distribution of this feature is for it to be present in the otarioids, but only rarely so in the phocids (Mivart 1885), a difference Howell (1928) attributed to details of the orbicularis oculi and possibly the frontalis muscles. Turner (1848) questioned the value of this character for discriminating between the pinnipeds as it was present both throughout the otariids and in representative phocids (, Hydrurga). A variable distribution in the pinnipeds is echoed by Hendey & Repenning (1972). Except for Hydrurga and Lobodon, the preorbital process is generally small in monachines, if not altogether absent, as in Leptonychotes, Monachus schauinslandi, and Monachus tropicalis (Mivart 1885; Hendey & Repenning 1972; de Muizon & Hendey 1980). Among phocines, Burns & Fay (1970) used the size of the preorbital process as one means of distinguishing between the closely related genera Pagophilus, Pusa, Histriophoca, and Phoca (listed in descending order of process size). In fissiped carnivores, the process is lacking in all but Lutra and Ursus, where it is rudimentary (Mivart 1885). In contrast to the observations of Mivart (1885), we found a distinct preorbital process in all fissiped taxa expect Procyon. The plesiomorphic condition is for a small process, with an increase to medium size denoting a synapomorphy of the lutrines and the Please note that t
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