[MM] Gobiconodon sp. (3)
DESCRIBER Cuenca-Bescós & Canudo, 2003
TIME Cretaceous Early
FOSSILSITE Artoles Formation, Vallipon, Teruel Province, Spain
FALL UNDER Gobiconodon borissiaki
Gobiconodon borissiaki (Trofimov, 1978) > Gobiconodon hoburensis (Trofimov, 1978 )[ >> Guchinodon hoburensis (Trofimov, 1978 )] > Gobiconodon hopsoni (Rougier, Novacek, McKenna and Wible, 2001) > Gobiconodon ostromi (Jenkins and Schaff, 1988) > Gobiconodon zofiae (Li, Wang, Hu & Meng, 2003) > Gobiconodon sp. (1) (Rougier, Novacek, McKenna & Wible, 2001) > Gobiconodon sp. (2) (Tang et al., 2001) > Gobiconodon sp. (3) (Cuenca-Bescós & Canudo, 2003 )
A gobiconodontid from Vallipón (Teruel, Spain) represents the first record of this family in Europe. The site has a di verse fossil assemblage mainly composed of isolated bones and teeth probably accumulated by tidal action and water streams in an ancient beach of upper Barremian, in the transitional marine−continental sediments of the Artoles Forma tion. The new gobiconodontid consist of an isolated upper molar, smaller in size than that element in other gobi conodontids, with a robust cusp A, characterised by lateral bulges on each mesial and distal flanges of that cusp, and a dis continuous cingulum raised at the lingual side. The occlusal outline is smooth compared with Gobiconodon borissiaki, Gobiconodon hoburensis, or Gobiconodon ostromi. The Gobiconodontidae record is exclusively Laurasiatic. The oldest gobiconodontid fossil remains are Hauterivian; though their probable origin has to be found at the Late Jurassic in Central Asia (as inferred from derived character of the first gobiconodontids as well as phylogenetic relationships). At the end of the Early Cretaceous they expanded throughout Laurasia as indicated by findings in Asia, North America, and Spain. Two dispersion events spread gobiconodontids: to the West (Europe) in the Barremian and to the East (North America) during the Aptian/Albian.
Description.—One left upper molariform, M3 or M4 (MPZ 2002/73) of small size. It has a robust cusp A, characterised by probably autapomorphic lateral bulges on each mesial and
distal flanges of that cusp. It has a discontinuous cingulum raised at the lingual side. The tooth is 1.67 mm long and 1.13 mm wide (Table 1). It is almost complete, only the
mesiolingual corner is broken, and a small portion of the anterolingual part of cusp B is missing. The tooth has two roots, the anterior one being broken. The posterior root is
complete and compressed anteroposteriorly. In oclusal view the crown is “pillow−shaped”, more or less rectangular, and somewhat constricted in the middle. The mesial half is transversely narrower than the distal. The labial side is more in dented than the lingual (Figs. 2–4). The tooth crown is fan shaped in labial and lingual views. The central cusp A is the highest point of the crown. The three main cusps: the anterior B, medial A, and pos terior C form a wide obtuse angle. Cusp A is more lingual with respect to cusps B and C. On the distal side the distal cingulum has a broad wear facet that may have had a cuspule D (Fig. 2A) with a lingual slope. Cusp A is the high est and the broadest with a small wear surface on its tip, and it has two mesial and distal bulges aligned anteroposteriorly with its tip, which gives it a massive ap pearance (Fig. 2A, B, D). Both protuberances are less visi ble but still noticeable in oclusal view, specially the distal one (Fig. 3). Cusp B is heavily damaged. Cusp C is about a third lower than the height of the main cusp A and has a distolingual wear facet. The cusps are separated by shallow incisions visible in both lingual and labial views. Thenotches have V−shape and they are less than 25% as deep as the cusps. The cingulum widens on the lingual side, where it has two small cingular cusps. The proximal cingular cusp forms the mesiolingual corner of the base of cusp A, and the other is distal and at the bottom between cusps A and C, slightly higher and taller than the proximal (Figs. 2A, B, C, 4B). A thin enamel layer, as observed in the broken part of cusp B (Fig. 4C, D), covers the crown. The effects of acid etching allowed us to study the internal structure of the enamel and dentine. The enamel is prismatic, with the prisms more or less perpendicular to the oclusal surface and the enamel−dentine junction arranged in a similar pattern de scribed as the radial type (Koenigswald and Clemens 1992). The enamel is thin compared with the massive dentine. The radial structure of the dentine can be seen in Fig. 4C. The pulp cavity is visible in the anterior part (Fig. 2E), one can see the thickness of the dentine compared to the cavity, indi cating that the molar belongs to an adult individual rather than to a juvenile.
Cuenca−Bescós, G. and Canudo, J.I. 2003. A new gobiconodontid mammal from the Early Cretaceous of Spain and its palaeogeographic implications. Acta Paleontologica Polonica 48 (4): 575–582.