Heterodontus rugosus (Agassiz, 1843)

Adolfssen, Jan S. & Ward, David J., 2015, Neoselachians from the Danian (early Paleocene) of Denmark, Acta Palaeontologica Polonica 60 (2), pp. 313-338 : 325

Heterodontus rugosus (Agassiz, 1843)

Fig. 5F–H .

1843 Acrodus rugosus sp. nov.; Agassiz 1843: t. 3, 148, pl. 22: 28, 29.

1889 Cestracion rugosus Agassiz ; Woodward 1889: 335.

1964 Heterodontus rugosus Agassiz ; Albers and Weiler 1964: 7, fig. 41a–c.

1977 Heterodontus rugosus Agassiz ; Herman 1977: 90, pl. 3: 5.

Material.—20 incomplete teeth from the Ce of Stevns Kridtbrud (MGUH 29848, MGUH 29849, MGUH 29850, GMV2012-68 [batch number]).

Description.—Dentition with strong ontogenetic heterodonty and disjunct monognathic heterodonty.Anterior teeth with six short and apical rounded cusps of lateral decreasing size. The lower crown of the labial face and the cusps are at an oblique angle to each other and whereas the cusps are smooth the lower crown has a strongly puckered ornamentation. The apron is broad and semicircular. The lingual face of the crown is smooth and convex, with a medio-lingual protuberance. The root is bilobed and slightly asymmetrical. The basal face is flat with a central foramen. The lingual face of the root has a protuberance and there is a foramen in each side of the lingual protuberance.

Lateral teeth are mesio-distally elongated, with a transverse crest. The transverse crest may have a cusp in anterior-lateral teeth. The labial face is more coarsely ornamented and steeper than the finer ornamented lingual face. The roots are missing in almost all of the lateral teeth, but appear to have been low and basally flat.

Remarks.—In Recent Heterodontus , there is strong ontogenetic heterodonty in all files but it is particularly evident in anterior files where the teeth undergo a reduction in lateral cusplets and likewise in the posterior teeth which loses their cusps and aquires a crushing morphology ( Reif 1976). This is evident in the sampled anterior teeth, indicating the presence of both juveniles and adults. Reif (1976) divided Recent Heterodontus into two groups based on their dentitions. The H. portusjacksoni group possess several files of low-crowned inflated lateral files with a straight, poorly developed carina. The H. francisci group possess narrower lateral teeth with a centrally placed, often sigmoidal carina, and a low centrally placed cusp and coarse ornamentation. According to this scheme, H. rugosus would belong to the H. francisci group.

Stratigraphic and geographic range.—Late Cretaceous: Campanian of France and Germany ( Thies and Müller 1993; Vullo 2005) and Campanian and Maastrichtian of Belgium (Agassiz 1843; Herman 1977; Bless et al. 1991) to the Dani- an (early Paleocene) of Denmark.

Figures

Fig. 5. Orectolobiformes and Heterodontiformes from the Danian of Stevns Kridtbrud, Kulstirenden, Faxe kalkbrud, and Terkelskov Kalkvaerk. A–E. Delpitoscyllium planum (Davis, 1890). A. MGUH 1400, holotype (Br2) anterior tooth in labial (A 1), basal (A 2), and lateral (A 3) views. B. OESM-10046-20 Br2) anterior tooth in labial (B 1), basal (B 2), and lateral (B 3) views. C. OESM-10046-21 (Br2) anterior tooth in labial (C 1), basal (C 2), and lateral (C 3) views. D. OESM-10046-19 (Br2) lateral tooth in labial (D 1), basal (D 2), and lateral (D 3) views. E. OESM-10046-22 (Br2) posterior tooth in labial (E 1), basal (E 2), and lateral (E 3) views. F–H. Heterodontus rugosus (Agassiz 1843). F. MGUH 29848 (Ce) anterior tooth in labial (F 1), lingual (F 2), and lateral F 3) views. G. MGUH 29849 (Ce) lateral tooth in occlusal view. H. MGUH 29850 (Ce) lateral tooth in labial (H 1), occlusal (H 2), and lateral (H 3) views., J. Heterodontus sp. I. MGUH 298451 (Br2) anterior tooth in labial view. J. OESM-10046-13 (Br2) lateral tooth in occlusal view.