Talmontopus tersi ” Lapparent & Montenat, 1967

Moreau, Jean-David, Vullo, Romain, Bichr, Elsie, Thomas, Jérôme, Gand, Georges, Gagnaison, Cyril, Barrier, Pascal & Néraudeau, Didier, 2024, Crocodylomorph and dinosaur tracks from the lowermost Jurassic of Le Veillon (western France): ichnotaxonomic revision of the type material (Lapparent collection), Geodiversitas 46 (8), pp. 343-366 : 359-360

“ Talmontopus tersi ” Lapparent & Montenat, 1967 (nomen dubium) ( Fig. 12 A-C)

Talmontopus tersi Lapparent & Montenat, 1967: 29-30 , pl. XII.1, fig. 17.

STATUS. — Subjective senior synonym of Kayentapus isp.

EXAMINED MATERIAL. — Holotype: ULB-04C02_A .

DESCRIPTION

The track ULB-04C02_A consists of a single, slightly longer than wide (L/W = 1.2), 26 cm long and 21.5 cm wide tridactyl track ( Fig. 12 A-C; Table 2 ). The angle between II and IV is large (II-IV = 64°). Digit imprints are quite thin and pointed. The traces of digits II and IV are straight and quite similar in length. The trace of digit III is the longest and is slightly curved. The digito-metatarsal base of digit IV is slightly more proximal than that of digit II. The free part of III is quite short (L/D = 2.8). The imprints of pads and claws are only poorly marked.

REMARKS

Based on the track ULB-04C02_ A, Lapparent & Montenat (1967) erected Talmontopus tersi . They justified the creation of “ T. tersi ” by a very high T value between thin tracks of digits, and the presence of a putative web mark.We consider the web mark drawn in fig. 17 of Lapparent & Montenat (1967) as a sedimentary structure that corresponds to a slight thickening of sediment preserved between the traces of digits (see also plate XII.1 inLapparent & Montenat 1967; ULB-04C02_A). Since ULB-04C02_A shows many characters of Kayentapus Welles, 1971 , we consider “ Talmontopus ” as a subjective senior synonym of this ichnogenus. Kayentapus differs from Grallator and Eubrontes in showing larger divarication angle II-IV and a smaller L/W ratio. Kayentapus was erected by Welles (1971) based on the type ichnospecies K. hopii Welles, 1971 from the Early Jurassic Kayenta Formation in Arizona. Two other ichnospecies were later described from Early Jurassic strata of the United States and Poland: K. minor ( Lull, 1953) Weems, 1987 and K. soltykovensis ( Gierliński, 1991) Gierliński, 1996 (firstly named Grallator (Eubrontes) soltykovensis in Gierliński 1991 and Gierliński & Ahlberg 1994), respectively ( Weems 1987; Gierliński 1996). Based on its D/W and (L-D)/W ratios (0.43 and 0.78, respectively), the track ULB-04C02_A fully falls within the morphological space of K. hopii ( Gierliński 1996: fig.1 andLockley et al. 2011: fig. 6B). However, K. hopii is clearly larger (L = 34.0-35.5) than ULB-04C02_A ( Fig. 4 ). It also differs from ULB-04C02_A in showing traces of digits that are slender and well individualised, and digito-metatarsal pads of the digit IV much more proximal. ULB-04C02_A is close to K. minor ( Fig. 4 ), however, it seems to differ from this ichnospecies in showing a higher D/W ratio (see Gierliński 1996: fig. 1 and Lockley et al. 2011: fig. 6B). K. slotykovensis differs from ULB-04C02_A in showing a smaller (L-D)/W ratio (see Gierliński 1996: fig. 1 and Lockley et al. 2011: fig. 6B).

Figures

FIG. 12. — Kayentapus isp.: A-C, track ULB-04C02_A (holotype of “Talmontopus tersi” that is here invalidated), photograph (A), DEM and false-colour depth map (B) and interpretative sketch (C). Scale bars: 10 cm.

FIG. 4. — Footprints from Le Veillon compared to tridactyl tracks from the Early Jurassic of the Causses Basin (based on data from Demathieu et al. 2002; Moreau et al. 2021) and the Early Jurassic of the eastern United States (based on data from Weems 1992, 2019; Gand et al. 2018): A, bivariate diagram L vs (L–D)/D; B, bivariate diagram L vs L/W. L in metres.