Dissacus serratus ( Chow and Qi 1978 )
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publication ID |
https://doi.org/ 10.4202/app.2008.0301 |
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persistent identifier |
https://treatment.plazi.org/id/634987DB-B575-F249-91D6-F7AF27A7F840 |
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treatment provided by |
Felipe |
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scientific name |
Dissacus serratus ( Chow and Qi 1978 ) |
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Dissacus serratus ( Chow and Qi 1978)
Fig. 15 View Fig .
Referred material: IMM−2004−SB−056, right jaw fragment with m1; IMM−2001−SB−061, right femur.
Description.—A lower jaw fragment with m1 ( Fig. 15A View Fig ) found at Subeng can be readily identified as Dissacus serratus , a small species of Dissacus previously reported from the nearby Nomogen and Bayan Ulan fauna ( Chow and Qi 1978; Meng et al. 1998).
An isolated femur ( Fig. 15B View Fig ) found in association with the jaw shows a morphology also seen in the femora other of Mesonychidae ( O’Leary and Rose 1995; Geisler and McKenna 2007), and is therefore also assigned to Dissacus serratus . The previously unknown femur of D. serratus is long and relatively slender. The diaphysis presents a slight Sshaped curve in an anteroposterior plane, and in cross section the depth is 1.5 times the width. The fovea on the femoral head is extensive but not open. The neck is very narrow in proximal view. The greater trochanter is slightly higher than the head and the trochanteric fossa is deep. On the lateral side of the shaft, a slight crest descends from the greater trochanter to the third trochanter. The third trochanter is prominent but less robust than in Pachyaena (see O’Leary and Rose 1995); it is situated at about one third of the way down the length of the shaft, but a robust crest continues farther from it to just past the midpoint of the shaft. The lesser trochanter is not well preserved, but seems to have been thin and moderately large, and projecting medially or posteromedially. The distal femur is as deep as it is wide. The patellar groove is long, narrow and well defined with the medial crest markedly higher than the lateral.
Discussion.— Geisler and McKenna (2007) recently described the new D. zanabazari from the Bumbanian of Naran Bulak, based on a partial skeleton. To their comparison of the dental morphology of D. zanabazari and D. serratus , we add that the lower molars of D. serratus can be further distinguished from D. zanabazari by the relatively lower paraconid and higher protoconid, the better−developed labial shearing crests and the presence of a small entoconid.
The femoral morphology of D. zanabazari and D. serratus seems closely similar. D. serratus possibly had a somewhat larger lesser trochanter, a less deep distal femur but a deeper and narrower distal trochlae than D. zanabazari , but
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