Strophodus atlasensis, Stumpf & Kettler & Kindlimann & Cuny & Kriwet, 2023

Stumpf, Sebastian, Kettler, Christoph, Kindlimann, René, Cuny, Gilles & Kriwet, JÜrgen, 2023, The oldest Gondwanan record of the extinct durophagous hybodontiform chondrichthyan, StrophoDUS from the Bajocian of Morocco, Swiss Journal of Palaeontology (5) 142 (1), pp. 1-15 : 3-5

Strophodus atlasensis sp. nov.

Figures 2 , 3 .

Diagnosis

A species of Strophodus that is characterized by the following unique combination of dental characters: Presence of a well-developed, heterodont crushing-type dentition; teeth of first lateral file short mesio-distally and slightly domed in labio-lingual view, with a nearly triangular occlusal outline; tooth crowns of first lateral teeth without transverse occlusal crest, but covered with a finely reticulate pattern; teeth of the second lateral file wide mesio-distally and bulbous without a dome in labio-lingual view, displaying a subrectangular occlusal outline with a slightly concave labial and a gently convex lingual edge; tooth crowns of second lateral teeth without transverse occlusal crest and covered with a finely reticulate pattern that turns into labio-lingually aligned bands along the lingual part of the crown; teeth of first posterior file shorter mesio-distally than labio-lingually long and elliptical in occlusal outline; tooth crowns of first posterior teeth slightly elevated and ornamented with a finely reticulate pattern; tooth crowns of second posterior teeth small and oval in occlusal outline with their long axes oriented obliquely, exhibiting a finely reticulate ornamentation pattern; tooth roots of second posterior teeth parallelogram-shaped in occlusal outline and protrude distally and slightly labio-lingually below the crown, meeting each other in an efficient interlocking manner.

Holotype and only known specimen

PIMUZ A/I 5181, an incomplete articulated dentition.

Type locality and horizon

Talsint, Figuig Province, Morocco; upper Agoudim Formation, Bajocian, Middle Jurassic.

Etymology

Te specific epithet refers to the High Atlas Mountains from which the holotype originates .

Nomenclatural act

Te published work and the nomenclatural acts it contains have been registered in ZooBank, the online registration system for the ICZN. Te ZooBank LSIDs (Life Science Identifiers) can be resolved and the associated information viewed through any standard web browser by appending the LSID to the prefix http://zoobank. org/. Te LSID for this publication is: urn:lsid:zoobank.org:pub:C987BC7F-F855-410D-9B62-7245A40F42E3 .

Description

Te holotype and only specimen of Strophodus atlasensis sp. nov., PIMUZ A/I 5181, is represented by an incomplete articulated dentition that contains a total of 21 crushing-type teeth, which are closely arranged in four well-defined tooth files, including two lateral and two posterior files ( Fig. 2 ). Te dentition, which exhibits a high degree of heterodonty, is here tentatively separated into comprising both functional and replacement teeth based on the presence or absence of dental wear patterns (see below). Te dentition is gently convex along its labio-lingual axis ( Fig. 2B, C, F, G ) and slightly twisted

( Fig. 2D, H ). Te tooth roots are still embedded in rock matrix or are just partially exposed. Whether the dentition belongs to the upper or lower jaw cannot be determined due to its incomplete preservation.

Figures

Fig. 2 Strophodus atlasensis sp. nov., PIMUZ A/I 5181, holotype, from the upper Agoudim Formation (Bajocian) near Talsint,Figuig Province, Morocco. Orthophoto (A–D) and ambient occlusion photogrammetric model with highlighted tooth crowns (E–H) in occlusal (A, E), mesial (B, F), distal (C, G) and oblique occlusal (D, H) views. Abbreviations: LF1, tooth crowns of first lateral file; LF2, tooth crowns of second lateral file; PT1, tooth crowns of first posterior file; PT2, tooth crowns of second posterior file

Fig. 3 Strophodus atlasensis sp. nov., PIMUZ A/I 5181, holotype, from the upper Agoudim Formation (Bajocian) near Talsint,Figuig Province, Morocco. Complete specimen (A) with close-up views of first lateral (B, C), second lateral (D–F) and first posterior teeth (G–I), plus close-up of second posterior tooth (J)