Carchariidae indet, 1841

Szabó, Márton, 2019, Middle Miocene (Badenian) chondrichthyan and osteichthyan remains from St. Margarethen (eastern Austria) in the vertebrate palaeontological collection of the Hungarian Natural History Museum, Fragmenta Palaeontologica Hungarica 36, pp. 53-90 : 59-65

Carchariidae indet . or Odontaspididae indet.

( Figs 16 –65)

Referred material – a slightly disarticulated, partial dentition surrounded by placoid scales and suggested portions of cartilage (VER 2020.69.1.), from which 15 placoid scales (VER 2020.70.1.–84.1.), 1 piece of stone matrix embedding at least 5 placoid scales (VER 2020.85.1.), and 6 pieces of suggested cartilage tissue (VER 2020.86.1.–90.1.) were isolated.

Description – Based on the visible crown portions, specimen VER 2020.69.1. ( Fig. 16 ) consists of at least 32 teeth, however, it is hard to tell how many teeth the broken root portions belong to. Some teeth are preserved in labial, while some in lingual aspect. Th e teeth represent the upper and lower anterior and lateral files, including the intermediate file of the upper dentition ( Figs 17–25 ). No posterior files are visible. All teeth which are embedded in lingual aspect, possess a smooth lingual crown face. Based on the variety of the observed tooth positions, VER 2020.69.1. represents a slightly disarticulated mixture of the upper and lower dentition.

A large number of placoid scales are visible in the embedding limestone matrix. Placoid scales were isolated from three areas around the dentition, where the scales are densely aggregated ( Fig. 26 ). It is noteworthy that placoid scales sparsely occur over a large part of the surface of the embedding piece of limestone. The isolated placoid scales represent four morphotypes. Morphotype 1 (isolated from areas I and III; see Figs 27–36, 49, 50) has drop- or arrowhead-shaped crown. Threefour anteriorly bulging, parallel folds are present on the apical surface, reaching from the anterior margin to the anteroposterior half of the crown. The crown of placoid scales representing Morphotype 2 (isolated from area II; see Figs 37–46) is circular in apical view. The anterior margin is weakly folded. Morphotype 3 (isolated from area III; see Figs 47, 48, 51–56) is similar to Morphotype 1 in having a pointed posterior edge, but the crown meets the base in a lower angle. This morphogroup seems to represent an intermediate form between the first and the fourth morphotype. Morphotype 4 (isolated from area III; see Figs 57, 58) has tricuspid crown, bearing an anteriorly bulging median keel, laterally flanked by parallel folds. The lateral folds diminish posteriorly, while the median keel reaches the posterior margin of the crown. The base of all morphotypes bears large foramina.

The suggested cartilage tissue of specimen VER 2020.69.1. is built up of mosaically adjacent units of irregular outline. The largest, and also the most well-preserved portions of the suggested cartilage are between the surface area I and III ( Figs 59–61 ). Pieces of this structure were also isolated for scanning electron microscopic photography (Figs 62–65).

Remarks – Based on genetic studies, STONE & SHIMADA (2019) resurrected Carchariidae for genus Carcharias to separate it from family Odontaspididae . However, tooth morphology of the here referred fossil taxa was a subject of many studies in the past (e.g. DE SCHUTTER 2011; REINECKE et al. 2011, 2014; BOR et al. 2012; CAPPETTA 2012), and differential tooth characteristics of the two families have not been detailed since the work of STONE & SHIMADA (2019). Except for the less-developed and low number of lateral cusplets (usually one pair in any teeth of specimen VER 2020.69.1.), the dental characteristics are comparable with those of A. vorax (see DE SCHUTTER 2011; BOR et al. 2012). The notably small size of the teeth refers specimen VER 2020.69.1. (and its isolated portions) to a juvenile individual, with assumedly less-developed dental characteristics. However, two different shark species sharing similar dental characteristics, while inhabiting the same environment is highly unlikely from the biological point of view (after REINECKE et al. 2011: 21), following its ontogenetic stage, an assignment of specimen VER 2020.69.1. (and its isolated portions) to A. vorax would be quite hazardous. As both Carchariidae and Odontaspididae are reported from St. Margarethen ( SCHMID et al. 2001; present study), here I find more appropriate to describe specimen VER 2020.69.1. with all of its isolated portions only as Carchariidae indet. or Odontaspididae indet. Differences in tooth morphology of these two, hardly separable families are not detailed yet, which is beyond the scope of the present study.

It is worth mentioning that placoid scales of Morphotype 2 are weakly reminiscent of scales/those of an embrional individual of the Oligocene-Miocene species C. gustrowensis ( HOVESTADT & HOVESTADT-EULER 2010, fi g. 6. 68.), in having a circular, anteriorly folded crown. REIF (1985) figured dermal denticles of the extant species Carcharias taurus , but they have a different morphology by having much stronger folds on the apical surface, reaching the posterior edge of the denticles.

Figures

Fig. 16. Carchariidae indet. or Odontaspididae indet. partial dentition, VER 2020.69.1. Scale bar: 20 mm

Figs. 17–25. Teeth in specimen VER 2020.69.1. – Fig. 17. Lower anterior (parasymphyseal) tooth in lingual aspect. – Fig. 18.?Upper anterior tooth in labial aspect. – Fig. 19.?Lower anterior tooth in labial aspect. – Fig. 20.?Upper anterior tooth in labial aspect. – Figs 21–22. Upper intermediate tooth in labial aspect. – Fig. 23. Upper lateral tooth in lingual aspect. – Fig. 24. Upper lateral tooth in lingual aspect. – Fig. 25. Lower lateral teeth in labial aspect. Scale bars: 2 mm

Fig. 26. Areas I–III of specimen VER 2020.69.1. from where placoid scales were isolated. – Figs 27–28. VER 2020.70.1. – Fig. 27. Apical view. – Fig. 28. Profile view. – Figs 29–30. VER 2020.71.1. – Fig. 29. Apical view. – Fig. 30. Profile view. – Figs 31–32. VER 2020.72.1. – Fig. 31. Apical view. – Fig. 32. Profile view. – Figs 33–34. VER 2020.73.1. – Fig. 33. Apical view. – Fig. 34. Profile view. – Figs 35–36. VER 2020.74.1. – Fig. 35. Apical view. – Fig. 36. Profile view. – Figs 37–38. VER 2020.75.1. – Fig. 37. Apical view. – Fig. 38. Profile view. – Figs 39–40. VER 2020.76.1. – Fig. 39. Apical view. – Fig. 40. Profile view. – Figs 41–42. VER 2020.77.1. – Fig. 41. Apical view. – Fig. 42. Profile view. – Figs 43–44. VER 2020.78.1. – Fig. 43. Apical view. – Fig. 44. Profile view. – Figs 45–46. VER 2020.79.1. – Fig. 45. Apical view. – Fig. 46. Profile view. – Figs 47–48. VER 2020.80.1. – Figs 49–50. VER 2020.81.1. – Fig. 49. Apical view. – Fig. 50. Profile view. – Figs 51–52. VER 2020.82.1. – Fig. 51. Apical view. – Fig. 52. Profile view. – Figs 53–54. VER 2020.83.1. – Fig. 53. Apical view. – Fig. 54. Profile view. – Figs 55–56. VER 2020.84.1. – Fig. 55. Apical view. – Fig. 56. Profile view.– Figs 57–58. VER 2020.85.1.– Fig. 57. Apical view. – Fig. 58. Profile view. Placoid scales of Morphotype 1: Figs 27–36, 49, 50; Morphotype 2: Figs 37–46; Morphotype 3: Figs 47, 48, 51–56; Morphotype 4: Figs 57, 58. Scale bars: 26: 5 cm; 27–46, 49–58: 200 Μm; 47: 1 mm; 48: 250 Μm

Figs 59–61. Close-up of VER 2020.69.1. between areas I and III, where large portions of the suggested fossilized cartilage tissue is exposed. – Figs 62–65. Scanning electron microscopic pictures of isolated pieces of the suggested fossilized cartilage tissue. – Fig. 62. VER 2020.86.1. – Fig. 63. VER 2020.88.1. – Fig. 64. VER 2020.89.1. – Fig. 65. VER 2020.90.1. Scale bars: 59–61: 2 mm; 62, 63: 200 Μm; 64: 100 Μm; 65: 250 Μm