Alephis boodon ( Gervais, 1853 )
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publication ID |
https://doi.org/ 10.5281/zenodo.5376630 |
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persistent identifier |
https://treatment.plazi.org/id/11352538-A718-FFF2-7150-F9B70215FCCA |
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treatment provided by |
Marcus |
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scientific name |
Alephis boodon ( Gervais, 1853 ) |
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Alephis boodon ( Gervais, 1853) ( Fig. 8 View FIG A-K)
MATERIAL EXAMINED. — Right P2; right m3; incomplete right m2; distal metacarpal; second phalanx ( MAA).
ALA-2, M1, and ALA-3, right m3 ( Gromolard 1981: pl. 3, figs 1, 2); incomplete left p4; incomplete left p3 ( MCNV).
M-2101, left M3; M-2430, astragalus; M-2434, astragalus; M-2114, astragalus; M-693, second phalanx ( MGM). Alc 1, incomplete left m3; Alc 2, incomplete P4 ( Gervais 1853: pl. V, fig. 2); Alc 3, incomplete left M; Alc 4, incomplete left m3; Alc 5, right m3 ( Gervais 1853: pl. V, fig. 8); Alc 6, incomplete left m3 ( Gervais 1853: pl. V, fig. 7); Alc 23, right m2 ( Gervais 1853: pl. V, fig. 6); Alc 9, proximal left metacarpal; Alc 8, right astragalus ( MNHN).
MEASUREMENTS. — See Appendix: Tables 4-7.
DESCRIPTION
The dentition of the Bovini from Alcoy is morphologically quite primitive when compared with the typical one of the current representatives of the tribe. Roughly speaking it is similar to that of the large sized Boselaphini although it shows slightly greater hypsodonty. The general characteristics are: moderate hypsodonty, lack of cement, quite flattened cones and conids.
Particularly the upper molars have a labial wall in which the external ribs of the cones are little marked, the lingual wall is bent and converges with the labial one. The fusion between the labial and lingual walls takes place at an advanced wear stage. The central valleys are half-moon-shaped and relatively simple. The ectostyle is poorly developed. Premolars with styles of moderate size, P2 quite long and with a well developed anterior lobe. The lower molars have a wavy lingual wall and conids with weak internal ribs.
Although the material is not very abundant, if we consider the size of the dentition ( Table 4), the fossils from Alcoy could belong to only one species Alephis boodon , slightly larger than the Bovini from Perpignan, presently classified as Alephis lyrix Gromolard, 1980 . Morphologically, there is some variability in the lower molars, particularly in the m3. In some individuals the caprine fold is strong whereas in others it is almost imperceptible, the development of the ectostylid is also variable.
Metacarpal: the specimen Alc 9 ( Fig. 9C, D View FIG ) is a 151 mm long proximal fragment of a left metacarpal. As in Alephis lyrix , the proximal epiphysis has both the facet for the triangular unciform and that of the magnotrapezoid, with convex dorsal and medial edges; nevertheless, this latter shows as in Parabos cordieri (Christol, 1832) , a strong concavity ( Gromolard 1981). The joint surface has a straight palmar edge and a more semicircular dorsal outline than in the afore-mentioned species, as a whole it shows great similarity to P. soriae Morales, 1984 from Venta del Moro.
The dorsal and palmar insertion tuberosities are very developed, especially that corresponding to the radial extensor muscle of the wrist; however there is no sign of a groove for the tendon of the lateral digit extensor muscle. The arterial dorsal groove is very thin and superficial. The palmar side of the diaphysis is flat except for the proximal central zone where there is a deep hollow.
The specimen M-698 consists of a distal fragment of metapodial, it is probably a metacarpal ( Fig. 8J View FIG ). The morphology of the distal ends corresponds to the type A of Köhler (1993) and is very similar, even in size, to Bos gaurus Smith, 1827 , but in the fossil from Alcoy the dorsal grooves are smaller and the external condyles are narrower and with a convex distal edge. In the proximal limb there are more differences partly derived from the greater width of the present specimen. This is more evident in the diaphysis, with a much more compressed section.
The dimensions of both epiphyses ( Table 5) coincide with those of A. lyrix and A. tigneresi Michaux, Aguilar, Calvet, Duvernois & Sudre, 1991 and are much greater than those of P. cordieri and to a lesser extent also greater than those of P.soriae . The values of the proximal and distal indices DAP/DT are in the average of the species from Roussillon, although they overlap with those of P. cordieri . On the contrary, in P. soriae these indices are clearly higher, although they are also within the range of variation of A. lyrix . In the diaphysis there is apparently a greater difference between P. cordieri , with a section more compressed anteroposteriorly, and A. lyrix , P. soriae and the species from Alcoy, which show greater DAP/DT values ( Fig. 9D View FIG ).
Astragalus ( Fig. 8K View FIG ): there are five astragali with different sizes and degrees of preservation; two of them are stored in the MNHN and three in the MAA. The smallest and most complete is M-2430. In all of them, the dorsal face has a strong medial process, a stop for the tibia, under which there is a relatively wide insertion surface that spreads transversely between the two trochleas. In the plantar face the stop facets are also very developed, although they are slightly variable, especially the distal lateral one. On the medial face the distal part is quite flat and the distal fossa is very small; the plantar process is little developed in the proximal part and the fossa is almost absent. However, in the lateral face, the projection of the edge of the plantar joint surface produces a very pronounced concavity and a strong proximal process more similar to that of P. cordieri than to that of A. lyrix . The outline of the proximal trochlea is, on the contrary, as in the latter species ( Gromolard 1981). The distal trochlea has diverging medial and lateral processes; the condyles are similar in width and separated by a very broad central groove.
Morphologically they do not show remarkable differences with regard to the astragali of the type Boselaphini from the upper Miocene. Gromolard (1980b, 1981) pointed out the difficulties to morphologically distinguish the astragali of Parabos cordieri , Alephis lyrix and the species from Alcoy. They are also very similar to those of P. soriae , the differences being details like the greater development of the medial fossa or the distal lateral condyle which is more prominent in this species, or differences in the development of lateral face relief: more moderate in the species from Venta del Moro, similar in Leptobos elatus (Croizet, 1853) from Villarroya, much more extreme in Bos Linnaeus, 1758 .
As for the size ( Table 6), the variability of the astragali from the Alcoy site is comparable to that existing in P. cordieri and A. lyrix (measurements in Gromolard 1980b; Gromolard & Guérin 1980), within the range of variation of the latter, although the smallest individuals coincide in their minimal values and therefore overlap with P. cordieri . The ratio between the distal width and the lateral length is similar in these three species ( Gromolard 1981), in P. soriae it is the same as the maximal values of P. cordieri and of A. lyrix and in Leptobos elatus (Villarroya) it is slightly higher ( Table 6).
Second phalanx (M-693) ( Figs 8H, I View FIG ; 9A, B View FIG ): the size and morphological characteristics are very close to those of a posterior phalanx of a female of Bos gaurus (MNCN) . It has a mixed morphology with the predominance of moderately developed type B characters combined with some type A ones ( Köhler 1993). Among type B characters are those related to the interdigital face, the relatively developed extensor dorsal process, the palmar and dorsal expansion of the distal joint surface, the absence of palmar sagittal fossa and the narrowing of the diaphysis in the median zone. Among type A characters are the presence of strong insertion marks for the interdigital ligaments and the superficial flexor of the fingers, and a large postarticular platform.
The outline of the proximal facets is closer to that of P. cordieri than to that of A. lyrix ( Gromolard 1981) , although in the fossil from Alcoy the external facet is less prolonged in the posterior part due to the strong reduction of the external tuberosity. This makes the proximal surface outline symmetrical. Something similar happens in Bos taurus Linnaeus, 1758 . Between the two facets there is a strong edge that ends in a process in the posterior part.
The dimensions of M-693 ( Table 7) are within the maximal values of A. lyrix , and even exceed them in length and proximal anteroposterior diameter. However the DT/DAP ratio in the epiphyses is close to the average value of these indices in P. cordieri , whereas in A. lyrix , the width is relatively greater; the opposite happens in P. soriae and in B. gaurus .
DISCUSSION
Morphologically the dentition of the Bovini from Alcoy is clearly distinguished from that of Leptobos Rütimeyer, 1877 , which is much more derived in the afore-mentioned characters, and is included in the same group as Parabos Arambourg & Piveteau, 1929 and Alephis . The differences from the species assigned to these two genera are difficult to evaluate because of the scarcity of the material from Alcoy and because some of the specimens figured by Gervais (1853) have not been found. The metrical differences pointed out by Gromolard (1980a, b) with regard to A. lyrix are minimal, and certainly the Bovini from Alcoy is close to the maximal values of Alephis lyrix , but only the P2 with a somewhat greater length and the M3 are out of the values range of the species from Perpignan. According to our opinion the morphological differences pointed out by Gromolard (1980a, b) between Alcoy and Perpignan are not very clearly explained and some of them could simply be due to the larger size of the species from Alcoy. Nevertheless it is probable that the premolars of the species from Alcoy were less reduced.
The size of the preserved postcranial elements of the species from Alcoy is similar to that of their homologues of A. lyrix . They are respectively 20% and 15% larger than the average of P. cordieri ( Gromolard 1981) and P. soriae . Although the sample is also poor in this case, there are both morphological and biometrical similarities with A. lyrix . Nevertheless some differences are also detected that make the identification of this species uncertain.
In the metacarpal, the shape and the proportions of the proximal facets are close to those of A. lyrix , whereas in the second phalanx this species has a less developed anteroposterior diameter in the epiphyses.
It shares with P.cordieri the presence in the metacarpal of a concave magnotrapezoid facet and convex distal condyles, but the species from Montpellier has a much more compressed diaphysis, with relatively smaller DAP and greater DT. This happens in a more pronounced way in Bos . In the phalanx there is a greater similarity in the shape of the proximal facets and in the proportions between this species and that of Alcoy with greater relative DAP values in the epiphyses. The same happens, more pronouncedly, in Bos .
Finally, the astragalus has a proximal trochlea as in A. lyrix , but a developed lateral proximal process like in P. cordieri . No biometrical differences between the three species were detected with the available data.
The species Parabos soriae shows the highest relative DAP values in the metacarpal and the lowest DT values in the second phalanx and in the astragalus.
The A/B morphology of the second phalanx, closer to B due to the lack of a groove for the lateral extensor of the fingers in the proximal metacarpal, suggest a somewhat less humid habitat than that attributed by Köhler (1993) to P. cordieri and P. soriae .
Gervais (1853) based Antilope ? boodon upon dentition and postcranial remains from the lignite beds of Alcoy (Alcoy-Mina), as a species close to that from Montpellier, Antilope cordieri . Depéret (1890) used the specific term to name the large bovid from Perpignan as Protoryx (Mesoryx) boodon . In revising the group, Gromolard (1980a, b) concludes that the forms belong to different species; he names the first one as Parabos ? boodon and creates a new genus and species, Alephis lyrix , for the second one.
Evidently there is an old systematic problem about the Alcoy material that particularly affects ruminants with cranial protuberances. The lack of information about the morphology of those protuberances in species whose definition is based upon dentition only creates important identification problems.
The case of the Bovini from Alcoy is paradigmatic. The dentition is only slightly larger than that of Alephis lyrix , and could be included within its maximal values, and morphologically is not very different despite the opinion of Gromolard (1980a, b). However we know nothing about the cranial morphology of Antilope ? boodon , and this makes the situation uncertain, since different bovid species based on the morphology of their horns (as it happens in other families of ruminants) can have metrically and morphologically very close dentitions, and with limited samples, they could be practically undistinguishable.
As already mentioned, Parabos and Alephis show the same dental pattern well differentiated from that of Leptobos and the more modern Bovini , but also somewhat different from that of the Boselaphini . They are more derived than the latter in their incipient hypsodonty, in the early fusion of upper molar internal and external lobes, in the development of strong ectostyles, in the tendency to the reduction of premolars, particularly the P2, etc. We do not agree with the separation of these two genera in different tribes, Boselaphini for Parabos and Bovini for Alephis , as proposed by Gromolard (1980a, b) and by Gromolard & Guérin (1980). Besides the general large size and the same dental pattern, Parabos and Alephis also share great development of the horns, which, although retaining a subtriangular transversal section, show a clear thickening trend. The basal position of Parabos with regard to the Bovini is well justified ( Geraads 1992), but according to our opinion Alephis is more probably phylogenetically very close to Parabos ( Duvernois 1990) . Thus, forms like Alephis tigneresi ( Michaux et al. 1991) indicate close relationship between these two genera.
In fact, the species from Alcoy is close to A. tigneresi because of the less reduced premolars and also the similarity of the postcranial skeleton, according to the scarce available data. Based on these reasons, we prefer to classify the form of Alcoy as Alephis boodon , thus keeping the validity of the other two species of the genus: Alephis lyrix and Alephis tigneresi .
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