Grallator maximus ” 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 : 358

“ Grallator maximus ” Lapparent & Montenat, 1967

( Fig. 10 )

Grallator maximus Lapparent & Montenat, 1967: 20-22 , pls X, XI.1, fig. 11.

STATUS. — Subjective junior synonym of Grallator minusculus ( Hitchcock, 1858) Demathieu, Gand, Sciau & Freytet, 2002 .

EXAMINED MATERIAL. — Holotype: ULB-04C13_B (plaster cast). — Other specimens: ULB-04C04_A_1 ; ULB-04C06_A ; ULB-04C10_B .

DESCRIPTION

The tracks are tridactyl, longer than wide (L/W = 1.5-(1.6)- 1.7), 26.0-(26.8)- 27.5 cm long and 15.5-(16.6)- 17.7 cm wide ( Fig. 10 A-F; Table 2 ). D is quite long (L/D = 2.9-(3.0)-3.2). Impressions of digits are large, separated, well defined and elongated. The traces of digits II and III are the smallest and the longest, respectively. The angle between digits II and IV is 30°-(33°)-37° ( Table 2 ). Impressions of digital pads are well preserved and are circular to oval. The position of the digito-metatarsal pad of digit IV is more proximal than that of digit II ( Fig. 10 A-F).

REMARKS

Based on this material, Lapparent & Montenat (1967) erected (without diagnosis) the ichnospecies “ Grallator maximus ”. These tracks being similar to G. minusculus ( Fig. 4 ), we consider “ G. maximum ” as a subjective junior synonym of this ichnospecies. Based on footprints from the Jurassic of the United States, Hitchcock (1858) first described such large tridactyl tracks under the name Brontozoum minusculum Hitchcock, 1858 that were renamed Anchisauripus minusculus Lull, 1904 by Lull (1904). Based on material from the Hettangian-Sinemurian of the Causses Basin, Demathieu (1993) identified tracks that show similarities with the type material of Anchisauripus minusculus . Since Anchisauripus is characterised by the occasional presence of a hallux trace ( Lull 1904), which is always absent in the material from France, Demathieu (1993), Demathieu & Sciau (1992) and Demathieu et al. (2002) used Grallator minusculus rather than Anchisauripus minusculus . Demathieu et al. (2002) emended the diagnosis of G. minusculus as follows: “ Large tridactyl tracks II-IV of bipeds with L × l = ca 300 × 200 mm, with large digits and well-marked pads. Claws are weakly developed and the digito-metatarsal pad of digit IV is often marked. The angle II-IV is 39° in average. The projection of III is low with a III/ D ratio around 1.93 ” (translated from French).

Figures

FIG. 10. — Grallator minusculus (Hitchcock, 1858), Demathieu, Gand, Sciau & Freytet, 2002: A-C, track ULB-04C13_B (plaster cast of the holotype of “G. maximus” that is here invalidated), photograph (A), DEM and false-colour depth map (B) and interpretative sketch (C); D-F, track ULB-04C10_B, photograph (D), DEM and false-colour depth map (E) and interpretative sketch (F). 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.