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. 2024 May 8;11(5):231788.
doi: 10.1098/rsos.231788. eCollection 2024 May.

Siwalik sabrecats: review and revised diagnosis of Megantereon fossils from the foothills of the Himalaya

Affiliations

Siwalik sabrecats: review and revised diagnosis of Megantereon fossils from the foothills of the Himalaya

Christopher M Stimpson. R Soc Open Sci. .

Abstract

The diagnosis of different fossil taxa in small collections from disparate geographical and temporal contexts is a common challenge in palaeontology. The likely number of morphospecies of the extinct sabretooth cat Megantereon is a classic example and subject of long-standing debate. While analyses of global fossil collections have provided insights and hypotheses, specimens from the foothills of the Himalaya-the Siwaliks-have been overlooked in recent treatments due to poor characterization and a confused taxonomic history. Here, this oversight is addressed. Craniodental fossils from the Siwaliks are revisited and their taxonomic status is reviewed. Morphological and metric characteristics are described, and qualitative and quantitative comparisons with congenerics are performed with published descriptions and datasets. The Lower Pleistocene Siwalik Megantereon are among the largest known forms in the genus. Advanced characteristics include reduced upper third premolars and long but comparatively narrow carnassial teeth. While dietary specialism can constrain morphological diversity, statistical analyses, including controls for body size effects, detected significant metric differences in the mandibles in comparison with congenerics. Within current paradigms, the status of Megantereon falconeri as a distinct morphospecies is upheld. A revised diagnosis is provided and the taxonomic affinities of M. falconeri are considered.

Keywords: Megantereon; Siwaliks; morphometrics; sabretooth cat.

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Conflict of interest statement

I declare I have no competing interests.

Figures

Figure 1.
Figure 1.
Geographical distribution of fossils of Megantereon spp. Late Pliocene/Lower Pleistocene: M. cultridens, Kuruksay Megantereon, M. whitei, M. ekidoit, M. hesperus; Lower Pleistocene: M. nihowanensis, Renzidong and Yanliang Megantereon, Java Megantereon, Siwalik Megantereon; later Lower Pleistocene: M. adroveri; Middle Pleistocene: M. inexpectatus. Taxonomic conventions adapted from [5].
Figure 2.
Figure 2.
Generalized sabrecat dentition to show characters in cheek teeth: (a) left upper, occlusal view; (b) left lower, occlusal view; (c) right upper, lingual aspect; and (d) left lower, buccal aspect. Adapted from [50].
Figure 3.
Figure 3.
NHMUK PV OR 39730 left maxilla of M. falconeri; (a) occlusal view and (b) buccal aspect. Scale bar = 20 mm.
Figure 4.
Figure 4.
Buccal, lingual and occlusal aspects of mandibles of M. falconeri: NHMUK PV OR 16554 (a, d, g); NHMUK PV OR 16557 (b, e, h); NHMUK PV OR 48929 (c, f, i); NMI NH F18579 (j–l). Scale bars = 20 mm.
Figure 5.
Figure 5.
Metric comparisons of the upper dentition in Megantereon fossils: (a) bivariate plot of raw measurements of third upper premolar length (P3L) and width (P3W); (b) bivariate plot of raw measurements of fourth upper premolar length (P4L) and width (P4W); (c) the proportion of P3L to P4L as a ratio; and (d) size-adjusted ranges of P4W (P4Wadj).
Figure 6.
Figure 6.
Metric comparisons of the lower dentition in Megantereon fossils: (a) bivariate plot of raw measurements of fourth lower premolar length (p4L) and width (p4W); (b) bivariate plot of raw measurements of first lower molar length (m1L) and width (m1W); and (c) bivariate plot of first lower molar length (m1L) and jaw depth (JDm1).

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