Folipistrix digitulus Kriwet, 2003, sp. nov.
Creators: name: Kriwet, Jürgen
Publisher: name: Zenodo
Year: 2003
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Elasmobranchii
Orectolobiformes
Brachaeluridae
Folipistrix
Folipistrix digitulus

description: Folipistrix digitulus sp. nov.   
Figs. 2D, 3A.  
 Holotype: SMNS 87861.   
 Paratype: SMNS 87862.   
 Type locality: Weilen unter den Rinnen, SW Germany.   
 Type horizon:“Opalinuston”,Dogger α,lowerAalenian,MiddleJurassic.   
 Etymology: The species name is derived from digitulus (m.), the Latin word for a little finger in reconsideration of the finger−like projected labial protuberance.   
 Occurrence: Only known from the type locality.   
 Diagnosis.—Same as for genus.   
 Description.—The holotype (Fig. 2D) is a small tooth with preserved crown and root. The crown is relatively high and triangular in labial view without lateral cusplets. There are also no lateral heels. The crown is rather compressed labio−lingually. The labial face is almost flat and only slightly cambered toward the lower part of the crown. There is a distinct, labially projecting protuberance with rectangular outline in labial view. A root buttress or the root itself does not support the protuberance. In lateral view, the well−developed protuberance juts labially being almost horizontal. The base of the tooth crown is concave in labial view and overhangs the root slightly. The cutting edge is well developed. It displays a few very coarse, irregular indentations giving the cutting edge a coarsely serrated, leaf−like appearance. The serrations are very coarse basally. The lingual face is more convex. There is no median uvula and the neck collar is very thin, nearly absent. There is no crown ornament or sculpture developed.   
The root is hemiaulacorhize with two broad, flattened lobes. In lateral view the root is more or less perpendicular to the tooth crown. The root lobes are slightly flared creating a faintly notched crown/root junction in labial view. In basal view, the root is V−shaped with a well−marked labial depression. The root lobes meet lingually to form a massive and broad lingual protuberance. A rather large medio−lingual foramen is present opening in the basal portion of the protuberance. The central foramen is small. There are two pairs of margino−lateral foramina. A rather large foramen opens basally on the surface of one of the root lobes.  
The paratype (Fig. 3A) is a fragmentary tooth. Most of the root as well as the basal parts of the crown are heavily damaged. However, the remaining part of the tooth exhibits the general morphology of the holotype, although the serration−like appearance of the cutting edges is less pronounced.  
 Discussion.—The overall morphology of the teeth is similar to that of orectolobiforms, e.g., hemiaulacorhize vascularisation pattern, well−developed labial root depression, well−developed labial protuberance not supported by the root. However, the absence of a lingual uvula is unusual for extant orectolobiforms, in which the uvula is supported by the lingual protuberance of the root (Herman et al. 1992). In the general tooth morphology the above−described specimens also resemble teeth of Squatina to some extend. However, the tooth morphology of Squatina is rather simple and very conservative. Consequently many isolated Squatina −like teeth from the Cretaceous and Jurassic have been assigned to squatinids (e.g., Thies 1983; Batchelor and Ward 1990; Biddle 1993; Rees 2002; Underwood 2002). This resulted in a taxonomic lumping of similar morphotypes. Leidner and Thies (1999) already pointed out that there might be more genera of squatiniforms present in the Late Jurassic. But the identification of isolated orectolobiform teeth from the Cretaceous and Jurassic also might cause problems. As a result, the true specific composition of orectolobiforms and squatiniforms in the Jurassic and also in the Cretaceous is probably obscured. The teeth of extant squatiniforms and orectolobiforms share some very important features so that Herman et al. (1992) concluded that Squatina could represent an orectolobiform. A very characteristic feature of teeth of Squatina is the morphology of the protuberance, which is rounded in basal view and well supported by the root. This pattern is also found in several Cretaceous species. However, in most if not all Jurassic Squatina spp., the labial protuberance is more rectangular and massive and well detached from the root. In addition, the labial root depression is much more pronounced in orectolobiforms than in extant Squatina species. The taxonomy of Late Jurassic specimens and species referred to Squatina is still in need of revision. The main difference between teeth of Squatina and the new taxon is the absence of lateral heels, the presence of a well−developed labial root depression and the labial protuberance, which is not supported by the root but well detached from the root depression. Unfortunately, the taxonomy of Jurassic orectolobiforms is still not fully understood. Consequently, the new genus is assigned to Orectolobiformes as incertae familiae.   
The teeth resemble those of some carcharhiniforms in the absence of a lingual uvula. However, the overall crown morphology and root vascularisation pattern suggests closer relationships with orectolobiforms.  
 The crown morphology resembles those of some other extant galeomorphs to some extent (e.g., Isistius, Carcharodon, Pterolamiops) and is indicative for a cutting−type dentition. A cutting−type dentition also occurs in larger extant orectolobiforms (Cappetta 1987).   
Fam. gen. et sp. indet.  
Fig. 3B, C.  
 Material.—Two isolated tooth crowns (SMNS 87863, SMNS 87864), “Opalinuston”, Dogger α, lower Aalenian, Middle Jurassic, Weilen unter den Rinnen, SW Germany.   
 Remarks.—Two very small isolated tooth crowns resemble those found in orectolobiform sharks. Both specimens are damaged and completely lack the root. The crowns are broadened mesio−distally with a very convex basal edge in labial view giving specimen SMNS 87863 a dagger−like appearance. The main cusp of this specimen is rather short and slender. There is a pair of small, slender and pointed lateral cusplets diverging slightly from the main cusp. The cutting edge is continuous between main and lateral cusplets. The labial crown face is narrow in lateral aspect.   
The second specimen (SMNS 87864), as far as can be reconstructed, resembles the first specimen. However, the basal edge of the labial face seems to be straighter and the main cusp is slightly bent distally. This may indicate a lateral jaw position whereas specimen SMNS 87863 might come from an anterior to antero−lateral position. Both tooth crowns are completely smooth.  
Identification on familiar, generic or even specific level of both specimens is impossible. Both specimens are very small and have been recovered only because of using a very small mesh width during sieving. Whether they represent teeth of juvenile or adult specimens is not discernable. Because of the small size, at least specimen SMNS 87864 may represent a juvenile specimen.
description: Published as part of Kriwet, Jürgen, 2003, Neoselachian remains (Chondrichthyes, Elasmobranchii) from the Middle Jurassic of SW Germany and NW Poland, pp. 583-594 in Acta Palaeontologica Polonica 48 (4) on pages 586-588, DOI: 10.5281/zenodo.13392170