Anatomy and phylogenetic value of the mandibular and coronoid canals and their associated foramina in proboscideans (Mammalia).
Ferretti, Marco & Régis Debruyne.
Zoological Journal of the Linnean Society 2011, 161(2):391-413.
DOI: 10.1111/j.1096-3642.2010.00637.x

Abstract

Characters associated with the mandibular canal are differently distributed among proboscidean lineages and provide useful information on the systematics and relationships of proboscideans. The aim of the paper is to describe the pattern of the mandibular canal and its associated foramina in proboscideans in order to fully appreciate the extent of interspecific variation of these structures within the group and to discuss its systematic and phylogenetic value. Outgroup comparison indicates that the condition presented by the basal proboscidean Phosphatherium is morphotypic for proboscideans. Primitive proboscidean characters are: the low position of the mandibular foramen, and its crescent-shaped outline, the occurrence of a coronoid foramen (canal), the occurrence of two lateral mental foramina, the posterior one at the level of (or slightly behind) the posterior margin of the symphysis, the anterior one in a more distal position, the absence of a medial mental foramen (MMF), the mandibular canal set just below the tooth row. The occurrence of a single lateral mental foramen might represent a shared derived character ofDaouitherium, Numidotherium, and Barytherium. A unique derived feature of the Elephantinae mandible is the occurrence of a medial mental foramen, on the medial side of the incisive part of the mandible. MMF has never been observed in other proboscideans excluding elephantines. The very high frequency of MMF observed in Mammuthus meridionalis-M. trogontherii-M. primigenius (>93 per cent of the studied specimens) could be considered a synapomorphy of this group.

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Depuis 2003, nous avons accumulé des centaines (que dis-je: des milliers) d’observations sur des mandibules de proboscidiens fossiles et actuels afin de tester nos hypothèses quant au statut diagnostique de certaines formes de ces caractères chez les mammouths.

Après avoir rapidement abordé le sujet dans ma thèse, et réalisé un poster avec Marco pour le IMC9 de Sapporo en 2005, nous allons enfin publier une version détaillée de cette analyse dans le Zoological Journal of the Linnaean Society, où notre article intitulé “Anatomy and phylogenetic value of the mandibular and coronoid canals and their associated foramina in proboscideans (Mammalia)” vient d’être accepté.

Abstract

Mitochondrial cytochrome b of the Lyakhov mammoth (Proboscidea, Mammalia): new data and phylogenetic analyses of Elephantidae.
Debruyne, Régis, Véronique Barriel, & Pascal Tassy.
Molecular Phylogenetics and Evolution 2003, 26(3):421-434.
DOI: 10.1016/S1055-7903(02)00292-0

Abstract

The phylogenetic relationships between recent Elephantidae (Proboscidea, Mammalia), that is to say extant elephants (Asian and African) and extinct woolly mammoth, have remained unclear to date. The prevailing morphological scheme (mammoth grouped with Asian elephant) is either supported or questioned by the molecular results. Recently, the monophyly of woolly mammoths on mitochondrial grounds has been demonstrated (Thomas et al., 2000), but it conflicts with previous studies (Barriel et al., 1999; Derenko et al., 1997).
Here, we report the partial sequencing of two mitochondrial genes: 128 bp of 12S rDNA and 561 bp of cytochrome b for the Lyakhov mammoth, a 49,000-year-old Siberian individual. We use the most comprehensive sample of mammoth (11 sequences) to determine whether the sequences achieved by former studies were congruent or not. The monophyly of a major subset of mammoths sequences (including ours) is recovered. Such a result is assumed to be a good criterion for ascertaining the origin of ancient DNA. Our sequence is incongruent with that of Yang et al. (1996), though obtained for the same individual. As far as the latter sequence is concerned, a contamination by non-identified exogenous DNA is suspected. The robustness and reliability of the sister group relation between Mammuthus primigenius and Loxodonta africana are examined: down-weighting saturated substitutions has no impact on the topology; analyzing data partitions proves that the support of this clade can be assigned to the most conservative phylogenetic signal; insufficient taxonomic and/or characters sampling contributed to former discordant conclusions. We therefore assume the monophyly of “real mammoth sequences” and the (Mammuthus, Loxodonta) clade.

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New mitochondrial data demonstrating a close relationship between Mammuthus primigenius (Blumenbach, 1799) and Loxodonta africana (Blumenbach, 1797).
Debruyne Régis.
in ‘The world of elephants’, Proceedings of the 1st international Congress, 2001. Consiglio Nazionale delle Ricerche, Rome, pp.630-632.

Abstract

The question of the phylogenetical relationships between recent Elephantidae has been raised on morphological but also molecular grounds. Mitochondrial data (cytochrome b gene particularly) either support or question the classical scheme which associates Mammuthus primigenius with the Indian elephant, Elephas maximus Linné 1758. Recent studies depict a closer relationship between mammoth and African elephant, Loxodonta africana. We report the partial sequencing of two mitochondrial markers from a 49,000 years old Siberian mammoth. The comparison of its sequence with 10 other mammoths and with African (both bush and forest forms) and Asian elephants gives weight to this hypothesis. However, a previous study of the same specimen (Yang et al. 1996) produced a highly divergent sequence that clusters with Indian elephants. The accuracy of the two alternative sequences is evaluated and leads us to the conclusion that the woolly mammoths form the monophyletic sister-group of African elephants on molecular grounds.

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The timing of early elephantine differentiation: the palaeontological record, with a short comment on molecular data.
Pascal Tassy & Régis Debruyne.
in ‘The World of Elephants’, Proceedings of the 1st international Congress, 2001. Consiglio Nazionale delle Ricerche, Rome, pp.685-687

Abstract

The differentiation of the extant genera Elephas and Loxodonta among the Elephantinae (including the extinct genera Primelephas and Mammuthus) occurred during the late Miocene. Earliest known Loxodonta is found in Baringo (Kenya) and Nkondo-Kaiso (Uganda) between 7.3-5.4 Ma. Earliest known Elephas is found at Lothagam (Kenya), circa 6-7 Ma. This paleontological record is in accordance with molecular data: mitochondrial DNA provide support for the estimation of an original split for (Mammuthus, Loxodonta) and (Elephas) dated between 5.6-7.0 Ma.

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Oral communication (in French): “Les secrets de l’ADN du mammouth de Liakhov : rebondissements dans la phylogénie des Elephantidae”

I responded to the invitation of Prof. Armand de Ricqlès to come and discuss the latest results in the phylogeny of Elephantidae based on ancient DNA sequences derived from mammoths and modern elephants.