megantereon cultridens (cuvier) (mammalia, felidae, machairodontinae) from plio-pleistocene deposits...

Paleontological Society

Megantereon cultridens (Cuvier) (Mammalia, Felidae, Machairodontinae) from Plio-PleistoceneDeposits in Africa and Eurasia, with Comments on Dispersal and the Possibility of a NewWorld OriginAuthor(s): Alan TurnerReviewed work(s):Source: Journal of Paleontology, Vol. 61, No. 6 (Nov., 1987), pp. 1256-1268Published by: Paleontological SocietyStable URL: http://www.jstor.org/stable/1305213 .Accessed: 18/05/2012 14:52

Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at .http://www.jstor.org/page/info/about/policies/terms.jsp

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range ofcontent in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new formsof scholarship. For more information about JSTOR, please contact [email protected].

Paleontological Society is collaborating with JSTOR to digitize, preserve and extend access to Journal ofPaleontology.

http://www.jstor.org

http://www.jstor.org/action/showPublisher?publisherCode=paleo

http://www.jstor.org/stable/1305213?origin=JSTOR-pdf

http://www.jstor.org/page/info/about/policies/terms.jsp

JOURNAL OF PALEONTOLOGY, V. 61, NO. 6, P. 1256-1268, 4 FIGS., NOVEMBER 1987

MEGANTEREON CULTRIDENS (CUVIER) (MAMMALIA, FELIDAE, MACHAIRODONTINAE)

FROM PLIO-PLEISTOCENE DEPOSITS IN AFRICA AND EURASIA, WITH COMMENTS ON DISPERSAL AND THE

POSSIBILITY OF A NEW WORLD ORIGIN

ALAN TURNER Department of Human Anatomy and Cell Biology,

University of Liverpool, Liverpool L69 3BX, England

ABSTRACT--African machairodont specimens previously referred to three species of Megantereon are considered to represent a single species in turn argued to be conspecific with the Eurasian species Megantereon cultridens (Cuvier). The area of origin of Megantereon remains unclear, but doubt is expressed about claims for an earliest appearance of the genus in North America. It is probable that the North American species M. hesperus is a junior synonym of M. cultridens.

INTRODUCTION

TWO RECENT publications discussing the machairodont genus Megantereon (Ficcarelli, 1979; Berta and Galiano, 1983) have referred to uncertainty about the precise number of species present in Africa. Both studies cite the opinion of Hendey (1974) that no more than one lineage may have occurred on the continent, but it remains apparent that a reevaluation of the relevant material is needed for full clarification. This paper offers such a reevaluation set against a brief review of the history of debate on the topic. The discussion is extended to include the relationship between African, Eurasian, and New World Megantereon, and the evidence for the origin of the genus.

Attention is concentrated on mandibles and lower dentitions. Clearly, taxonomic deci- sions based on such restricted portions of the skeleton are less than ideal, but the limitation is imposed by the material since no other elements are so frequently represented.

The following abbreviations, used in the text and tables in conjunction with specimen numbers, indicate institutional catalogue references and, where appropriate, site or locality: BM, British Museum (Natural His- tory); E, Elandsfontein, and L, Langebaanweg, South African Museum, Cape Town; ER, East Rudolf (Turkana), National Museum of Ken- ya; IGF, Institute of Geology, Florence; PE, Les Etouaires, Perrier, Universit6 Claude- Bernard, Lyon; QSV, Saint-Vallier, Mus6um d'Histoire Naturelle, Lyon; STS, SK, KA, KB,

and TM are respectively specimens from Sterkfontein, Swartkrans, Kromdraai A and B, and Schurveburg in the Transvaal Mu- seum, Pretoria.

PREVIOUS WORK

In 1937, Broom created a new species of cat, "Felis" whitei, based on a fragment of mandible from Schurveburg in the Trans- vaal. He placed the genus in inverted com- mas since, as he put it, "Though it clearly belongs to a different genus it is at present quite impossible to say whether this genus has or has not been described." Two illustrations of the specimen, now catalogued as TM 856, are shown in Figure 1; 1.1 is a copy of Broom's original drawing and 1.2 is the author's own representation. Delson (1984) has recently suggested a date close to 2.0 MYBP (million years before present) for the Schurveburg deposits, based on a biostratigraphic analysis of African fossil cercopithe- cids.

In 1939, Broom again mentioned and briefly described the Schurveburg cat, but at this point argued that it might prove to belong to a species of the genus Meganthereon (sic). At the end of his discussion he mentioned that a mandible "most probably" belonging to the same species had been found at Sterkfontein.

In 1946, Broom and Schepers figured the new Sterkfontein specimen and named it Me- gantereon gracile, but gave no description. In 1948, Broom returned to the problem with a somewhat fuller discussion of the specimen.

Copyright ? 1987, The Paleontological Society 1256 0022-3360/87/0061-1256$03.00

PLIO-PLEISTOCENE FELIDAE 1257

3

c~5cm

4 5 1t d0

67

FIGURE 1--South African specimens of Megantereon discussed in the text. 1, TM 856 (redrawn after Broom, 1936); 2, TM 856; 3, STS 1558; 4, KA 64 right mandible and M, with reversed left P3 and P4; 5, SK 337; 6, cast of Elandsfontein unnumbered right mandible with P4 and M1, together with E 3060, a left horizontal ramus and condyle (hatched lines) reversed and superimposed; 7, Kromdraai BE3 5224.

The mandible, now catalogued as STS 1558, is shown in Figure 1.3. It comes from Mem- ber 4 of the Sterkfontein deposit, for which a central age estimate of 2.6 MYBP has been made (Vrba, 1982). Broom separated his two species on the basis of three major features: 1) the size and development of the fourth premolar, where STS 1558 was said to be shorter and to have the middle and both posterior cusps less developed than in TM 856; 2) the size and proportions of the carnassial, where that of TM 1558 was argued to be longer and to have a more developed posterior portion (the protoconid); and 3) the depth and anterior extent of the masseteric fossa in STS 1558, said to contrast with a complete absence of the fossa in TM 856.

Ewer (1955) proposed a third species, Me- gantereon eurynodon, on the basis of specimen KA 64, a much crushed skull and mandibles found, together with some damaged cervical vertebrae and portions of the scapula

and humerus, at Kromdraai A. The deposit is undated (Vrba, 1982), but formation between 1.5 and 2.5 MYBP would not be in- consistent with the mammalian assemblage. A composite dental reconstruction, using the distal portion of the right mandible and carnassial together with reversed drawings of the left premolar three and four, is shown in Fig- ure 1.4. Ewer argued that differences in proportions of the mandible ramus and of the teeth ruled out conspecificity with M. gracile. That discussion mentioned M. whitei only in passing, but clearly implied acceptance of it as a third species of Megantereon.

Ewer (1955) also gave a brief description of a specimen from Swartkrans Member 1, SK 337, an anterior mandible fragment con- taining the third premolar and the major portion of the fourth, shown here in Figure 1.5. The deposit is dated to approximately 1.7 MYBP (Vrba, 1982). As Ewer argued, the morphology of the mandible and teeth clearly

1258 ALAN TURNER

TABLE 1- Measurements (in mm) of lower dentitions and mandibles in Megantereon specimens. L and B are length and breadth of teeth; C-cd, distance from anterior surface of canine to center of condyle; HPC, height of coronoid process; P3-M,, distance from anterior of P3 to posterior of M,; DEPTH A and P, mandibular depths anterior to P3 and posterior to M, respectively; BP4, mandible breadth below P4; a signifies approximate. Sources as indicated.

Ci P3 P4 M1 DEPTH B L B L B L B L B C-cd HPC P3-M, A P P4

African (author; * Leakey, 1976) ER 793 10.0 7.0 - - 14.4 6.4 17.1 8.1 135.0 a44 a41 26.9 30.2 12.8 ER 701* - - - - - - 20.0 8.8 - - - - - - E 3060 - - - - 15.0 8.1 20.6 8.9 - 48.9 - - - - KA 64 - - - - 17.0 - 19.6 9.0 - 55.0 a45 - 34.0 - STS 1558 - - - - 13.3 6.9 19.3 8.3 - - - - a27 13.2 TM 856 - - 6.6 3.9 14.5a - 17.6 8.5 - - - - - - SK 337 - - 5.8 3.5 - 7.5 - - - - - - - - KB 5224 - - - - - - 24.5 11.7 - - - - - -

Italian (Ficcarelli, 1979) IGF 827 - - - - 19.6 9.2 23.1 11.0 - - - - - - IGF 826 - - - - - - 23.0 10.4 - - - - - - IGF 829 - - - - - - 18.4 9.3 - - - - - - IGF 12485 - - - - 18.0 8.0 22.1 10.0 - - - - - - IGF 4711 - - - - 19.2 8.5 - - - - - - - - IGF 4709 - - - - 19.0 8.0 20.0 9.5 - - - - - -

Spanish (Kurten and Crusafont-Pair6, 1977; no catalogue number) La Puebla - - - - - - 19.6 9.1 - - - - -

French (author) QSV 146 10.2 7.0 12.4 6.5 17.8 8.6 18.6 8.7 - - 48.4 29.8 27.6 14.8

identifies the specimen as Megantereon, but she did not refer it to her new species from Kromdraai.

Hendey (1974) described material from the Cape Province site of Elandsfontein previously identified, but undescribed, by Bon6 and Singer (1965) as Megantereon gracile. The deposits are undated, but it is clear that a considerable time depth is represented and that the Megantereon material is most probably of early Pleistocene age (Hendey, per- sonal commun.). In addition to postcranial elements, the material consists of the condyle and ascending ramus of a left mandible (3060) together with a cast of the cheek teeth and portion of the horizontal ramus of an unnumbered right mandible no longer in the collection of the South African Museum. Since, as Hendey stressed, the two specimens appear to come from the same individual, they are shown here in Figure 1.6 as a composite reconstruction and referred to in Table 1 as E 3060. Hendey argued that all of the South African specimens most probably belonged to one lineage, but concluded that a further examination of all the relevant material would be necessary to resolve the ques-

tion of specific status. He therefore refrained from identifying the Elandsfontein material to species.

Leakey (1976) described machairodont material from the Koobi Fora Upper Mem- ber of East Africa (Vondra and Bowen, 1978), deposits currently dated to between 1.88 and 1.39 MYBP (Brown et al., 1985). Leakey referred the material to Ewer's Megantereon eurynodon. She noted variation, not only between the East and South African material but also between the East African specimens, but concluded that all were members of the same lineage. A drawing made from a cast of one of Leakey's specimens, ER 793, a mandible, is given in Figure 2.1. In the same vol- ume, Howell and Petter (1976) recorded Me- gantereon from the Usno and Shungura Formations in the Omo Group of East Africa, dated between 3.5 and 2.3 MYBP (Brown et al., 1985), but did not allocate the specimens to species. Both they and Leakey suggested that Megantereon was recorded from Bed I at Olduvai by Ewer (1965), but Ewer's description states unequivocally that identification of the specimens to genus was not possible.


Ficcarelli (1979, P1. 5, fig. 6) illustrated an undescribed mandible fragment from the Awash deposits in the Afar region of Ethiopia that he and Torre had identified as Megan- tereon from a photograph submitted to them. A current age estimate for the deposits, which are thought to be correlated with Members D and E of the Shungura sequence, is 2.4 MYBP (Kalb et al., 1982; Brown et al., 1985). The specimen, in which the beginning of the anterior mandibular flange may be clearly seen, is reproduced here in Figure 2.2 from the illustration given by Ficcarelli.

Most recently, Vrba (1981) recorded a new specimen of Megantereon from the E3 Mem- ber of the Kromdraai B australopithecine site, thought to date to around 2.0 MYBP (Vrba, 1982). The material, although fragmentary, consists of most skeletal parts of a single individual. The damaged left carnassial and fragment of the left ascending ramus of the mandible are shown together in Figure 1.7. Vrba discussed previous views about specific identification, and noted Hendey's suggestion for a single South African lineage. Hen- dey (1974) made no suggestion about the species name, refraining as he did from giving the Elandsfontein specimen a specific desig- nation, but he did make clear the fact that M. whitei should be included in the lineage. If all the South African specimens were to be assigned to a single South African species, the name whitei would take precedence over gracile or eurynodon.

DISCUSSION

Two issues are raised by the work sum- marized above: 1) the taxonomic status of the members of the African Megantereon sample, and 2) their relationship to Megan- tereon elsewhere. It is clear that opinion fa- vors interpretation of the African specimens as members of a single lineage, but that some hesitation remains over formally uniting the specimens in one species. Variation within the available sample appears to be the major reason for this hesitation.

Figures 1 and 2 show that there is considerable variation in the size of the specimens and in the size and form of the lower premolars. This is particularly true in the case of the fourth premolar, and is also seen in the case of the third premolar when one com-

2 0 1 2 3 4 5cm

?? ? i 1

FIGURE 2--East African specimens of Megantere- on discussed in the text. 1, ER 793 drawn from a cast; 2, unnumbered specimen from Afar (redrawn after Ficcarelli, 1979).

pares the specimen from Afar with those from South Africa. Available measurements for the various specimens are given in Table 1, together with their sources. Ficcarelli (1979) stressed the extent of similar dental variation in European Megantereon, but argued that the degree of dental specialization in these animals would lead one to expect such intra- specific differences in the anterior cheek teeth.

Therefore, addressing first the question of the relationship between the African specimens, can the erection of three species for the South African material be defended? If we consider the supposed distinction between Megantereon whitei and M. gracile, it is apparent that none of the differences proposed by Broom can be substantiated. As may be seen in Figure 1.1 and 1.2, Broom's sketch of TM 856 did not show the damaged nature of the specimen. It is clear that consideration of the matrix-filled splits in the fourth premolar substantially affects the profile reconstructed by Broom, and reduces the difference between the two specimens in this feature. The same is true of the carnassial, where rec- ognition of the split between paraconid and protoconid alters the apparent proportions of the tooth, and the contrast with STS 1558, considerably. The supposedly absent masseteric fossa on TM 856 is in fact present, although difficult to depict in the drawing in Figure 1.2. As Broom (1939, p. 332) pointed

1260 ALAN TURNER

out, the mandible is broken and the pieces displaced, added to which there is barely enough of the mandibular corpus to reveal a masseteric fossa. But examination of the fossil shows that a concavity does exist in the buccal surface below the carnassial, of fully adequate size for a masseteric fossa equal to that in STS 1558 at the same point. If the proposed distinctions between TM 856 and STS 1558 are thus rejected, then the similarities would suggest that they are conspecific.

Ewer (1955, p. 608) based her distinction between Megantereon gracile and her new species M. eurynodon on two features of STS 1558 and KA 64: the relative proportions of the lengths of the lower fourth premolar and carnassial, and the depth of the mandible. She quoted figures of 70 percent and 24.4 mm respectively for the premolar: carnassial ratio and mandibular depth below M, in STS 1558, versus 86 percent and 27.5 mm for the re- spective measurements in KA 64. Three points may be raised against such a distinction. First, the premolar: carnassial ratio for TM 856, Broom's M. whitei, which Ewer considered to be a valid third species, is about 82 percent. If such a figure is to be considered at least partially diagnostic, then Ewer should surely have concluded that KA 64 and M. whitei were probably conspecific, yet she did not. Second, such an unqualified use of the depth of the mandible for taxonomic distinction takes no account of the effect of the relative sizes of the two individuals nor of their relative ages; on the basis of evident tooth wear in Figure 1, the Sterkfontein individual is likely to have been younger at death than KA 64. But the third point is the most important. Employing such figures to separate two specimens into distinct taxa while making no allowance for within-population variation cannot be considered valid. There is simply no justification, on the evidence presented, for inferring that STS 1558 and KA 64 belonged to different species and that they in turn differed from M. whitei. It therefore seems that the previously presented arguments for the presence of three species of African Megantereon may certainly be rejected.

The Swartkrans mandible fragment SK 337, which Ewer did not allocate to any of the proposed African species of Megantereon,

clearly does not differ in any significant way from the other South African material discussed above. The outline of the broken fourth premolar is very similar to the equivalent tooth of STS 1558, and the ascending fragment of the anterior portion of the horizontal ramus also matches very well with that region of the more complete East African specimen from Koobi Fora, ER 793, shown in Figure 2.1. However, one might still argue that the African specimens of Megantereon exhibit an unusual degree of variation, particularly when the Afar mandible in Figure 2.2 and the large specimen KB 5224 from Kromdraai B are taken into account. But no author appears to have considered the possible role of sexual dimorphism in producing the pattern of variation seen. Indeed, the only reference to sexual dimorphism in Megantereon that has been found in the literature is that of Viret (1954, p. 75) who, speaking of variation in the Eu- ropean material, recognized that "Sans doute, le petit nombre de documents ne permet pas de conclusions formelles, et les differences dues au sexe viennent encore compliquer les comparaisons." That statement could equally well have been made about the African material. We can most conveniently deal with the question of the role of sexual dimorphism in conjunction with the second issue raised by the discussion in the preceding section, the relationship of African specimens to Me- gantereon from elsewhere.

Ewer (1955) was the first worker to consider the South African specimens against a wider background of other machairodont material. She compared the Kromdraai A specimen with the European species Megan- tereon cultridens (Cuvier, 1824, partim), the senior synonym of M. megantereon Croizet and Jobert, 1828 (Ficcarelli, 1979), and concluded that it differed at the species level. Those differences consisted of a wider and shorter upper canine in KA 64, and hence the name eurynodon, together with a less de- pressed mastoid and glenoid apophyses and a longer metacone (metastyle) for the upper carnassial than in the European species. Ewer went on to argue that the Kromdraai specimen had greater similarities with machairodont material from Nihowan in China identified as Megantereon (Machairodus) nihowanensis by Teilhard de Chardin and Piveteau (1930). However, Viret (1954) and Ficcarelli (1979)


TABLE 2-Measurements (in mm) of upper canine and upper carnassial in Megantereon specimens. L and B are length and breadth of teeth at crown base; Ba, anterior breadth of carnassial across protocone; Bbl, breadth across blade; Lp, length of parastyle; Lm, length of metastyle. Source author.

C5 P4

L B L Ba Bbl Lp Lm

Italian IGF 816 24.6 11.9 IGF 827 35.4 14.2 11.0 12.0 13.2 IGF 830 24.4 12.3 IGF 830 31.9 12.4 11.2 11.6 12.5

IGF 15355 30.0 14.5 9.8 10.9 12.0 IGF 4712 35.5 11.8 10.5 12.5 13.4

French QSV 147 20.7 10.5 QSV 1150 29.5 14.0 9.4 11.2 11.8

QSV 145 29.8 14.6 9.6 11.4 11.5 PE 211229 18.9 9.2

Spanish (Museum d'Histoire Naturelle, Lyon; no catalogue number) Villaroya 18.0 9.3 Villaroya 29.7 14.0 9.5 11.1 11.9

African KA 64 25.0 12.0 KA 64 29.8 10.8 9.4 10.4 12.1

have both suggested that the Nihowan material is probably no more than a geographic variant of M. cultridens. That view is accepted here because it is clear, as first pointed out by Schaub (1934) and noted by Ewer (1955, p. 609), that the Nihowan specimens were given specific status on the basis of error. Skull II (Teilhard de Chardin and Piveteau, 1930, P1. 22, figs. 2, 4) is clearly a Homo- therium Fabrini, 1890, while the remaining specimens are indeed Megantereon. The authors' discussion (1930, p. 117) of the relationship of their species notes the overall similarities in size and morphology between M. nihowanensis and M. cultridens, but draws a distinction largely on the basis of the short and crenulated canine that clearly belongs to the Homotherium. The basis for the separa- tion is simply invalid. It would also seem that the middle Pleistocene specimens from Lo- cality 1 at Zoukoudian, in China, referred by Teilhard de Chardin (1939) to Megantereon inexpectatus, are no more than larger ex- amples of M. cultridens.

Ewer did not compare her South African specimens with machairodont material from the Siwaliks. The generic and specific iden- tities of the Siwalik machairodonts have been confused, and have caused confusion, in the literature for a number of years, as may be seen in the discussions by Mathew (1929), Pilgrim (1932), and Colbert (1935). As late as 1979, Ficcarelli concluded that the specimens discussed by these authors were related

to Homotherium rather than to Megantereon. More recently, Petter and Howell (1982) have reassessed the Siwalik machairodont material, and have concluded that Megantereon is indeed represented. They decided to refer specimens of Megantereon to M. falconeri Pomel, 1853, rather than to M. cultridens, largely on the basis of size, although the difference between European and Siwalik specimens in P4 and

Ml lengths shown by the

authors in their figure is not great. They acknowledged that the morphological similarities to the European material are considerable, and conceded that reference to a subspecies of cultridens would be equally plausible. The author has recently seen the British Museum Siwalik specimens used by Petter and Howell, and can see no reason to separate them from M. cultridens. However, doubts remain about their referral of one of the specimens, BM 48929, a fragmentary left mandible with broken P4 and M , to Megan- tereon. The specimen does not appear to have had a mandibular flange, but its broken nature makes certainty on the matter rather difficult.

In her comparisons with the Eurasian specimens, it would seem that Ewer may have attached insufficient weight to the possibility of infraspecific variation in her material, particularly in view of the small available sample of complete upper canines, the extent of variation likely in upper carnassial proportions, and the state of specimen KA 64. Inferences

1262 ALAN TURNER

I p

1 2 3 4 2c

o'[: a: 4? sem

FIGURE 3-European specimens of Megantereon discussed in the text. 1, QSV 146, Saint Vallier, France (drawn from a photograph after Viret, 1954); 2, IGF 827, Upper Valdarno, Italy (redrawn after Ficcarelli, 1979).

based on the relative positions of the glenoid apophyses and the mastoid in such a crushed specimen are at best hazardous. The author has no figures for upper canine height in Eu- ropean specimens, but does have length and breadth measurements taken at the enamel base as well as a series of measurements taken on upper carnassials. These measurements are given in Table 2, and it may be seen that the length of the canine for KA 64 (Ewer's "width") simply falls at the end of the range. The measurements for the upper carnassial show considerable variation in the proportions of that tooth, and KA 64 does not have an unusually long metastyle.

As a further aid to comparisons between African and European specimens, two mandibles of European Megantereon cultridens are shown here in Figure 3. QSV 146 is from the French site of St. Vallier (Viret, 1954) and IGF 827 from the Italian Upper Val- darno Tasso Faunal Unit (Ficcarelli, 1979), with approximate dates of just after 2.5 and 1.5 MYBP, respectively (Azzaroli, 1977, 1983). Both specimens have a larger third premolar than is seen in the South African material, but show considerable similarity with the specimen from Afar shown in Figure 2.2. On that basis one might wish to argue that the European and Afar specimens are

distinguishable from the South African specimens, but the level at which that distinction should be set is not clear. Nor is the possible effect of sexual dimorphism easy to assess. That sexual dimorphism is likely to be in- volved is implied by the differences in relative tooth sizes seen in the Koobi Fora specimen in Figure 2 in comparison with the Afar fossil, unless one chooses to argue that the taxonomic distinction occurs at some point between Koobi Fora and the Afar.

To permit some assessment of the possible extent of sex-based variation in the Megan- tereon material, Figure 4 shows lower carnassial measurements of African and Euro- pean specimens in comparison with a sexed sample of modem leopards, Panthera pardus (L.), from the southwestern Cape, the Trans- vaal, and Malawi. The point of the comparison is that the leopard is of sufficiently similar overall size to the fossil species to provide a reference point for judgments about size variation in a fossil species for which sexual dimorphism is an unknown variable. More- over, the Cape leopards are known to be on average smaller than those from the more northerly areas, so that a geographic size cline is built into the comparison to take account of probable size clines in the fossil sample. Summary statistics for the leopard sample are given in Table 3.

Figure 4 shows that the Kromdraai B specimen is very much larger than the rest of the African specimens. However, the Italian sample, augmented by a Spanish and a French specimen, shows a possible bimodal grouping that bridges much of that gap. Considered against the pattern seen in the modern leopard sample, the size variation in the sample of African and European Megantereon would not be excessive for sexual dimorphism.

One possible objection to sexual dimorphism as an explanation for the pattern of size variation would be the implausibility of finding only the smaller, presumably female, specimens at the majority of African sites. However, that objection is less serious than it appears. The Afar specimen is not shown in Table 1 nor in Figure 4 because no published measurements are available. It is shown in Figure 2 increased to the stated natural size with respect to ER 793 from the illustration given by Ficcarelli (1979), but it is not possible to ensure that the result is complete-


12

--i E

z 10

8 0 0o

o**

C o O o O 8 0 ?W ? 0

0

I I I I I I I I I I

16 18 20 22 24

LENGTH M1 (mm)

FIGURE 4 -Length and breadth of lower carnassials. Closed circles, modem leopard males; open circles, modem leopard females; closed stars, African Megantereon; open stars, Italian Megantereon; open triangle, Spanish Megantereon; open square, French Megantereon. Details of Megantereon specimens given in Table 1. Summary statistics of leopard sample given in Table 3.

ly accurate. However, even if the scaling is not precise, the relative proportions of the teeth are sufficiently apparent for present purposes and the evident length of the carnassial, in the vicinity of 22 mm, would place the specimen close to the larger size group. Taken together with specimen KB 5224, that gives a ratio of two "males" to six "females" in the African sample, a perfectly acceptable result in such a small sample.

In view of the questionable nature of the published distinctions, and of the parallels between the observed size range of the fossils and the known sexual dimorphism of modern leopards, it would therefore seem that Afri- can specimens of Megantereon may most log- ically be referred to the Eurasian species M. cultridens.

ORIGINS OF AFRICAN MEGANTEREON

Specific identity of Eurasian and African Megantereon raises the question of dispersal: is the species an immigrant to or an emigrant from Africa? The earliest clear appearance of Megantereon in Africa is in the Usno For- mation of the East African Omo Group, for

which the current age estimate is approximately 3.1 MYBP, although it is possibly present in Member B of the Omo Shungura Formation at 3.5 MYBP (Howell and Petter, 1976; Brown et al., 1985). It may be present at Laetoli close to 3.7 MYBP (Barry, in press), but the material is a single fragmentary right 13, and the identification insecure (see summary of African large carnivore appearances in Turner, 1985).

Appearance outside Africa has recently been reviewed by Ficcarelli (1979), Petter and

TABLE 3--Length, L, and breadth, B, (in mm) of lower carnassials in modem male and female leopards. M, mean and standard error; SD, standard deviation; CV, coefficient of variation; OR, observed range; N, number of specimens. Source author.

M SD CV OR N Male

L 18.35 ? 0.25 1.20 6.6 15.2-19.9 24 B 8.63 ? 0.13 0.66 7.6 7.5-10.0 24

Female L 16.74 ? 0.31 1.06 6.32 14.7-18.1 12 B 7.76 ? 0.15 0.50 6.49 7.0-8.6 12

1264 ALAN TURNER

Howell (1982), and Berta and Galiano (1983), and it is clear that the genus enjoyed both a New World and an Old World distribution. In the Siwaliks, Megantereon appears in deposits assigned to the Pinjor Faunal Stage of Pilgrim (Petter and Howell, 1982). In a recent review ofSiwalik biostratigraphy, Barry et al. (1982) have proposed absolute dates for Si- walik deposits. The authors stress that their dates of 2.9 and 1.5 MYBP may nevertheless be placed on Pinjor material. As Barry et al. pointed out, the Siwalik mammal fauna at around 2.9 MYBP includes species that seem to be of African origin, so that immigration of Megantereon from that continent would be fully consistent with the pattern shown by other taxa.

Berta and Galiano (1983) referred to the French material from Les Etouaires as the earliest dated Eurasian specimen at 3.4-3.5 MYBP, based upon the K/Ar estimates quoted by Savage and Curtis (1970). How- ever, the age of the Les Etouaires fauna has recently been questioned, most recently by Thouveny and Bonifay (1984) who point out that a figure of 2.5-2.6 MYBP may also be possible. Berta and Galiano went on to claim that the earliest known Megantereon of all comes from the North American upper Bone Valley Formation of Florida. They argued for an age close to the Hemphillian-Blancan boundary for the assemblage, on which they placed a date of 4.5 MYBP, and referred the specimen from there, a left ramal fragment with P3, P4, and a broken MI, to M. hesperus (Gazin, 1933), a species known from a small number of other Blancan deposits that probably date to after 3.4 MYBP. The Bone Valley specimen implies an American origin, with a dispersal into Eurasia and Africa and a coincident speciation.

However, two points may be raised against that interpretation. The first concerns the identification of the Bone Valley specimen. The drawing presented by Berta and Galiano (1983, fig. 1) shows a fragmentary mandible in which the anterior portion deepens slightly but which has no real anterior mandibular flange of the kind normally seen in Megan- tereon, although an outline of a small one is reconstructed on the drawing. Instead of the more characteristic single, large mental foramen of Megantereon, the specimen has

three small ones. The P3 is large, and the anterior and main cusps of the P4, although well developed, are not relatively high, in contrast with those usually seen in Megan- tereon. Berta and Galiano (1983, p. 895) argue that "the structure and proportions of P3-4 are most similar to those ofM. cultridens from Saint-Vallier, France," referring to the specimen QSV 146 illustrated here in Figure 3.1. The author's own comparisons, with the original and with the photograph given in Viret (1954, Pl. 13, fig. 2), suggest that is not the case. The broken carnassial of the Bone Valley mandible appears to have been high, with a paraconid that was short in relation to the overall length of the tooth and with the angle between paraconid and protoconid seemingly relatively acute, features which would be consistent with referral to Megan- tereon. The dorsal ridge in the diastema between the canine alveolus and P3 is said to be present but less developed than in other specimens referred to M. hesperus and in other species of Megantereon. Unfortunately, the ascending ramus is missing, so that it is not possible to see if it was of the characteristi- cally short type seen in Megantereon. Berta and Galiano (1983, p. 896) concluded their description of the Bone Valley specimen by saying that it was assigned to M. hesperus because of its similarity to the referred mandible from Broadwater, Nebraska, also figured by them. They took the view that differences between the two specimens are of "minor taxonomic significance." In the author's view, the illustrations and description show few points of similarity; the Broadwater mandible is clearly Megantereon on the basis of characters absent in the Bone Valley specimen.

If the Bone Valley specimen is not Megan- tereon, two possible alternatives may be suggested. First, in its overall features as judged from the drawing, the remaining portion of the mandible looks remarkably like some of the specimens of Dinofelis from the South African early Pliocene site of Langebaanweg, particularly L-20284 (Hendey, 1974, fig. 36). The Langebaanweg specimens have a well- developed P3, a relatively low-crowned P4, a high carnassial with a relatively short paraconid and a relatively wide angle between paraconid and protoconid, a mandible in


which the anterior portion deepens without the development of a flange and which has multiple mental foramina, and a clear but only moderately developed dorsal ridge in the post-canine diastema. Only in the suggestion of a relatively acute angle between the paraconid and protoconid of M, does the Bone Valley specimen appear to have features that align it with Megantereon. Dino- felis is known in North America from the Blancan type locality of Blanco, Texas (Kur- ten, 1973; Kurt6n and Anderson, 1980), although the age of the deposit is unclear.

The second possible alternative is that the mandible belongs to one or other of the species variously referred to the genera Parama- chaerodus Pilgrim, 1931, and Pontosmilus Kretzoi, 1929. Berta and Galiano (1983, p. 896) provide a concise discussion of the confused history of nomenclature of the species in these genera, which they include in the tribe Metailurini. Briefly, Pilgrim (1931) argued that all should be placed in Parama- chaerodus with considerable synonymizing at the species level, while Kretzoi (1929) wished to restrict membership of that genus to one species, P. pilgrimi, with the rest retaining specific status in a new genus, Pontosmilus. For present purposes, the point is that two mandibles from Pikermi in the British Mu- seum collection, BM 8959, identified as Paramachaerodus orientalis by Pilgrim (1931) and as Pontosmilus schlosseri (Weithofer, 1888) by Kretzoi (1929), also appear rather similar to the Bone Valley mandible. The right one of the pair has a complete symphysis, which deepens and has a strong dorsoventral ridge but lacks a Megantereon-like flange. Two mental foramina are present. The P3 is well developed and backward raked, and P4 is elongated and narrow but with a relatively low main cusp. The carnassial has a short paraconid, and the protoconid and paraconid form a relatively acute angle. The canine is relatively flattened, and has a rather gracile crown with fine crenulations. Neither of the genera to which the specimens have been referred have had species referred to them from North American deposits. The Pikermi assemblage is placed within the Turolian land mammal stage of the upper Miocene (Savage and Russell, 1983). A reappraisal of the Bone Valley mandible, based on comparisons with

Dinofelis and Paramachaerodus/Pontosmi- lus, might prove valuable.

The second point to be made concerns the specific identity of Megantereon hesperus. Kurten and Anderson (1980, p. 186) argued that the species is closely related to the Eu- ropean M. cultridens, and suggested that further study might indicate specific identity. The type specimen of M. hesperus, a fragment of right mandible bearing a slightly worn carnassial from Hagerman, Idaho, was described by Gazin (1933) who referred it to Machairodus Kaup, 1833. The tooth shows a number of features, such as a backward tilt, a short paraconid and an acute angle between paraconid and protoconid, which align it with Megantereon. Gazin (1933, p. 256) noted the close correspondence between the specimen and European M. cultridens, but concluded that "heretofore Megantereon has not been recognized in North America and at present there is no certain evidence to show that the small Idaho machairodont belongs to this genus." The logic of excluding the first find of a known taxon in a new area for that taxon simply because it has not been previously recorded from the area is at best doubtful. Had Megantereon been known in North America, then Gazin would presumably have referred the specimen to it, perhaps even to the European species.

Schultz and Martin (1970) referred the Broadwater mandible mentioned above to Megantereon hesperus, amending Gazin's placement of the type in Machairodus in the process but not aligning the North American material with the European species. Berta and Galiano (1983, p. 894) offered a distinguishing diagnosis of M. hesperus on the basis of a primitively larger lower canine and P3, the development of a prominent groove on the medial surface of the mandible, and a stron- ger ridge in the post-canine diastema of the mandible. However, on the same page they also argued that, in comparison with their Bone Valley specimen, the ridge is "better developed in the Broadwater specimen and other Megantereon species." It is therefore difficult to see how the ridge can be of diagnostic value, particularly when the feature is well developed in the African specimens ER 793 and SK 337. The claim for greater size of P3 in M. hesperus loses its force when the

1266 ALAN TURNER

variability in development of anterior cheek teeth noted for the European specimens by Ficcarelli (1979) is acknowledged. In any event, much of the evidence for that character comes from the Bone Valley specimen. The claim for a larger lower canine is based on the Broadwater specimen, and takes no account of population variability. Only the groove on the medial side of the mandible seems to be a distinguishing feature of the North American material, but whether such a character is sufficient for specific status must be open to serious question.

If the Bone Valley mandible is removed from Megantereon, and if the earlier dates for Les Etouaires are considered suspect, then Megantereon from the East Africa deposits of Shungura B or Omo Usno must be considered the oldest dated material. An earliest record in Africa would be in accord with the pattern of immigration from that continent seen in the Siwalik assemblages. However, it is clear that first appearances in Eurasia and North America may lie very close in time to those in Africa, and it would be unwise to assume that the true pattern is known. An analysis of machairodontine relationships might offer some guidance, but the data for this are somewhat inadequate. Ficcarelli (1979, p. 20) concluded that "little or nothing can be said on the possible phyletic relationships between Megantereon and the Pontian specimens," but that may be a slight over- statement. With reservations about the specific identity of M. hesperus and rejection of the three African species accepted by them, the author would agree with many of the points made in the discussion on relationships presented by Berta and Galiano (1983, p. 896-897). However, the suggestion by Beaumont (1978) that Pontosmilus/Para- machaerodus may be the primitive sister taxon of Megantereon is here favored. Berta and Galiano (1983, p. 897) rejected that proposal because of the presence of dental serrations in Pontosmilus, the absence of which in Me- gantereon they interpret as a primitive reten- tion. The assumed irreversibility of such character states is a major part of the cladistic methodology, but in the final analysis must be seen as a guiding rule rather than an absolute fact. Unfortunately, accepting Ponto- smilus/Paramachaerodus as a primitive sister taxon of Megantereon offers little further as-

sistance in assessing the area of origin. It was clearly present in Eurasia, but the African record prior to the Pliocene is simply too poor for reliable judgments about presence or absence. Howell (1982) suggested that a Paramachaerodus may be present in the Sa- habi assemblage, but the material consists of unidentified post-cranial specimens. Inter- estingly, Berta and Galiano (1983, p. 896) suggested that Pontosmilus may prove to be congeneric with Metailurus Zdansky, 1924. Specimens referred to the latter genus are re- ported from Eurasian and a small number of African deposits of Miocene age, although neither Pontosmilus/Paramachaerodus nor Metailurus appear to have been recorded in North America (Savage and Russell, 1983). However, if the Bone Valley specimen should prove to be a member of Pontosmilus/Para- machaerodus, then it becomes impossible even to eliminate North America as an area of origin.

In conclusion, the following amended diagnosis of Megantereon cultridens is offered.

Order CARNIVORA Bowditch, 1821 Family FELIDAE Gray, 1821

Subfamily MACHAIRODONTINAE Gill, 1872 Genus MEGANTEREON

Croizet and Jobert, 1828 Type species. -Megantereon cultridens

(Cuvier, 1824, partim). Junior synonyms. -M. megantereon Croi-

zet and Jobert, 1828; M. whitei (Broom, 1937); M. gracile (Broom and Schepers, 1946); M. eurynodon Ewer, 1955; M. falconeri Pomel, 1853; M. nihowanensis (Teilhard de Chardin and Piveteau, 1930); M. inexpectatus (Teilhard de Chardin, 1939); ?M. hesperus (Gazin, 1933).

Lectotype. -IGF 816, upper right canine. Type locality. - Tasso faunal unit of the

Upper Valdarno (Ficcarelli, 1979). Diagnosis. -A medium-sized, sexually di-

morphic cat; short, high skull, triangular in profile with convex dorsal outline; extended glenoid apophyses; limbs and feet short and powerful, the forelimbs more so than the hindlimbs; tail reduced in length; upper canines elongated, compressed and curved; crenulations absent on all teeth; long post- canine diastema; upper and lower second premolars lost; upper and lower third pre-


molar present and functional but very variable in size; P4 protocone developed but variable in size; M' present but reduced; P3-M, backward raking; main cusp of P4 high crowned; M, lacking talonid or metaconid, paraconid shorter than protoconid and form- ing a relatively acute angle with it; mandible with short coronoid process, strong and ver- tical symphysis with enlarged flange extend- ing well below the ventral margin of the horizontal ramus; single large mental foramen.

Known distribution. --Blancan, North America; Villafranchian, Europe; Villafran- chian-Biharian, Asia; middle Pliocene-lower Pleistocene, Africa.

ACKNOWLEDGMENTS

I am grateful to B. Hendey and B. Kurten for useful comments on my conclusions and for their critical reading of earlier versions of the manuscript. I thank R. Ballesio (Univer- site Claude-Bernard, Lyon), A. Currant (Brit- ish Museum), G. Ficcarelli and D. Torre (Florence), B. Hendey (South African Mu- seum), J. Maquire (University of the Wit- watersrand), and M. Phillipe (Museum d'Histoire Naturelle, Lyon) for access to fossil and comparative material and for discussion. J. Barry kindly made copies of his work on the Laetoli carnivores available to me in advance of publication.

REFERENCES

AZZAROLI, A. 1977. The Villafranchian stage in Italy and the Plio-Pleistocene boundary. Gior- nale di Geologia, 41:61-79.

1983. Quaternary mammals and the "end- Villafranchian" dispersal event--a turning point in the history of Eurasia. Palaeogeography, Pa- laeoclimatology, Palaeoecology, 44:117-139.

BARRY, J. C. In press. Large carnivores (Canidae, Hyaenidae, Felidae) from Laetoli. In M. D. Leakey and J. M. Harris (eds.), The Pliocene Site of Laetoli, Northern Tanzania. Oxford Uni- versity Press, London.

- , E. H. LINDSAY, AND L. L. JACOBS. 1982. A biostratigraphic zonation of the Middle and Up- per Siwaliks of the Potwar Plateau of northern Pakistan. Palaeogeography, Palaeoclimatology, Palaeoecology, 37:95-130.

BEAUMONT, G. DE. 1978. Notes complemen- taires sur quelques F6lid6s (Carnivores). Ar- chives des Sciences Geneva, 31:219-227.

BERTA, A., AND H. GALIANO. 1983. Megantereon hesperus from the late Hemphillian of Florida with remarks on the phylogenetic relationships

of machairodonts (Mammalia, Felidae, Ma- chairodontinae). Journal of Paleontology, 57: 892-899.

BONE, E. L., AND R. SINGER. 1965. Hipparion from Langebaanweg, Cape Province and a re- vision of the genus in Africa. Annals of the South African Museum, 48:273-397.

BROOM, R. 1937. On some new fossil mammals from limestone caves of the Transvaal. South African Journal of Science, 33:750-769.

. 1939. A preliminary account of the Pleis- tocene carnivores of the Transvaal Caves. An- nals of the Transvaal Museum, 19:331-338.

1948. Some South African Pliocene and Pleistocene mammals. Annals of the Transvaal Museum, 21:1-38.

- , AND G. W. H. SCHEPERS. 1946. The South African Fossil Ape Men. The Australopitheci- nae. Transvaal Museum Memoir 2, 272 p.

BROWN, F. H., I. McDOUGAL, T. DAVIES, AND R. MAIER. 1985. An integrated Plio-Pleistocene chronology for the Turkana Basin, p. 82-90. In E. Delson (ed.), Ancestors: The Hard Evidence. Alan Liss Inc., New York.

COLBERT, E. H. 1935. Siwalik mammals in the American Museum of Natural History. Trans- actions of the American Philosophical Society, 26, 401 p.

CROIZET, J. B., AND A. C. G. JOUBERT. 1828. Re- cherches sur les ossements fossils du department du Pay-de-D6me, 1, Delahayes, Paris, 224 p.

CUVIER, G. 1824. Recherches sur les ossements fossils, oi Il'on r6tablit les characteres de plusiers animaux dont les r6volutions du globe ont de- truit les especes, 5, d'Ocagne, Paris, 547 p.

DELSON, E. 1984. Cercopithecid biochronology of the African Plio-Pleistocene: correlation among eastern and southern hominid-bearing localities, p. 199-218. In P. Andrews and J. L. Franzen (eds.), The Early Evolution of Man. Courier Forschungsinstitut Senckenberg, 69, Frankfurt.

EWER, R. F. 1955. The fossil carnivores of the Transvaal caves: Machairodontinae. Proceed- ings of the Zoological Society of London, 125: 587-615.

. 1965. Large Carnivora, p. 19-22. In L. S. B. Leakey (ed.), Olduvai Gorge, 1951-1961. Vol. 1. Cambridge University Press, Cambridge.

FICCARELLI, G. 1979. The Villafranchian machairodonts of Tuscany. Paleontographica Italica, 71:17-26.

GAZIN, C. L. 1933. New felids from the upper Pliocene of Idaho. Journal of Mammalogy, 14: 251-256.

HENDEY, Q. B. 1974. The late Cenozoic Carniv- ora of the southwestern Cape Province. Annals of the South African Museum, 63:1-369.

HOWELL, F. C. 1982. Preliminary observations on Carnivora from the Sahabi Formation (Lib- ya). Garyounis Scientific Bulletin, Special Issue 4:49-61.

1268 ALAN TURNER

-, AND G. PETTER. 1976. Carnivora from Omo Group formations, Southern Ethiopia, p. 314- 331. In Y. Coppens, F. C. Howell, G. L. Isaac, and R. E. F. Leakey (eds.), Earliest Man and Environments in the Lake Rudolph Basin. Uni- versity of Chicago Press, Chicago.

KALB, J. E., ET AL. 1982. Fossil mammals and artifacts from the Middle Awash gravels. Na- ture, 298:25-29.

KRETZOI, N. 1929. Materialien zur phylogene- tischen Klassifikation der Aeluroideen. 10th International Zoological Congress, Budapest, 1927, p. 1293-1355.

KURTEiN, B. 1973. The genus Dinofelis (Carniv- ora, Mammalia) in the Blancan of North Amer- ica. The Pearce Sellards Series, 19:1-7.

, AND E. ANDERSON. 1980. Pleistocene

Mammals of North America. Columbia Uni- versity Press, New York, 442 p.

S, AND M. CRUSAFONT-PAIRO. 1977. Villa- franchian carnivores (Mammalia) from La Puebla de Valverde (Teruel, Spain). Commen- tationes Biologicae Societas Scientiarum Fen- nica, 85:1-39.

LEAKEY, M. G. 1976. Carnivora of the East Ru- dolph succession, p. 302-313. In Y. Coppens, F. C. Howell, G. L. Isaac, and R. E. F. Leakey (eds.), Earliest Man and Environments in the Lake Rudolph Basin. University of Chicago Press, Chicago.

MATHEW, W. D. 1929. Critical observations upon Siwalik mammals. Bulletin of the American Museum of Natural History, 56:437-560.

PETTER, G., AND F. C. HOWELL. 1982. Un felid6 machairodonte des formations plio-pleistocenes des Siwaliks: Megantereon falconeri Pomel/=M. sivalensis (F. et C.)/. (Mammalia. Carnivora. Felidae.) Academie des Sciences, Comptes Ren- dus Hebdomadaires des Seances, Serie III, 295: 53-56.

PILGRIM, G. E. 1931. Catalogue of the Pontian Carnivora of Europe. British Museum (Natural History), London, 174 p.

1932. The fossil Carnivora of India. Pa- laeontologia Indica, 18:1-232.

POMEL, A. 1853. Catalogue methodique et de- scriptif des vert6bres fossils decouverts dans le basin hydrographique superieur de la Loire et de l'Allier. Annales Scientifiques Litteraires et Industrielles de l'Auvergne, 26:81-229.

SAVAGE, D. E., AND G. H. CURTIS. 1970. The Villafranchian Stage-Age and its radiometric dating. Geological Society of America Special Paper, 124:207-231.

-, AND D. E. RUSSELL. 1983. Mammalian Pa-

laeofaunas of the World. Addison-Wesley Pub- lishing Co., London, 432 p.

SCHAUB, S. 1934. Observations critiques sur quelques Machairodontides. Ecologae Geolo- gicae Helvetiae, 27:399-406.

SCHULTZ, C. B., AND L. D. MARTIN. 1970. Ma- chairodont cats from the early Pleistocene Broadwater and Lisco local faunas. Bulletin of the Nebraska University State Museum, 9:33- 38.

TEILHARD DE CHARDIN, P. 1939. On two skulls of Machairodus from the lower Pleistocene beds of Choukoutien. Bulletin of the Geological So- ciety of China, 19:235-256.

- , AND J. PIVETEAU. 1930. Les mammiferes fossiles de Nihowan (Chine). Annales de Pa- 16ontologie, 19, 134 p.

THOUVENY, N., AND E. BONIFAY. 1984. New chronological data on European Plio-Pleisto- cene faunas and hominid occupation sites. Na- ture, 308:355-358.

TURNER, A. 1985. Extinction, speciation and dispersal in African larger carnivores, from the late Miocene to Recent. South African Journal of Science, 81:256-257.

VIRET, J. 1954. Le loess a bancs durcis de Saint- Vallier (Dr6me) et sa faune de mammifbres Vil- lafranchiens. Nouvelles Archives du Museum d'Histoire Naturelle, Lyon, 4:1-200.

VONDRA, C. F., AND B. E. BOWEN. 1978. Stra- tigraphy, sedimentary facies and paleoenviron- ments, East Lake Turkana, Kenya, p. 395-414. In W. W. Bishop (ed.), Geological Background to Fossil Man. Scottish Academic Press, Edin- burgh.

VRBA, E. S. 1981. The Kromdraai australopithecine site revisited in 1980; recent investigations and results. Annals of the Transvaal Museum, 33:17-60.

-.1982. Biostratigraphy and chronology, based particularly on Bovidae, of southern Af- rican hominid-associated assemblages, p. 707- 752. In H. De Lumley and M-A. De Lumley (eds.), Proceedings of Congres International de Paleontologie Humaine, Vol. 2. Union Inter- national des Sciences Pr6historiques et Proto- historiques, Nice.

MANUSCRIPT RECEIVED 14 JUNE 1985 REVISED MANUSCRIPT RECEIVED 26 MAY 1987

megantereon cultridens (cuvier) (mammalia, felidae, machairodontinae) from plio-pleistocene deposits...

Documents