Cretalamna gertericorum, Siversson & Lindgren & Newbrey & Cederström & Cook, 2015
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publication ID |
https://doi.org/ 10.4202/app.2012.0137 |
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persistent identifier |
https://treatment.plazi.org/id/B63E4546-4335-FF85-FCCB-F9046C8B59CB |
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treatment provided by |
Felipe |
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scientific name |
Cretalamna gertericorum |
| status |
sp. nov. |
Cretalamna gertericorum sp. nov.
Fig. 11 View Fig .
1977? Cretolamna appendiculata var. appendiculata (Agassiz, 1843)
[partim]; Herman 1977: 210–216, pl. 9: 2c.
Etymology: Named after Gert De Bie and Eric Collier, who collected most of the Cretalamna teeth from the SECAB Quarry, Bettrechies, examined herein.
Type material: Holotype: Lower right, posteriorly situated lateropos-
1
2
3
terior tooth, UM-BET 5 ( Fig. 11G View Fig ). Paratypes: WAM 13.5.8–12, UM-BET 4 ( Fig. 11A–F View Fig ).
Type horizon: Tourtia de Bettrechies , early Turonian, Late Cretaceous .
Type locality: SECAB quarry, Bettrechies , northern France .
Material.— Type material only. Diagnosis. —Anterior teeth with slender, elongated cusps. Basal view of root triangular in upper and lower anterior teeth. Upper lateroposterior teeth from posterior half of inferred lateroposterior hollow with concave labial profile and broad, strongly distally curved cusp in labial/lingual views. Cusplets relatively upright in lateroposterior teeth but divergent in anterior teeth. Median indentation of basal edge of root small and tightly curved in lateroposterior teeth.
Description.—Second upper anterior tooth file: A complete tooth, 27 mm high, is referred to the A2 position ( Fig. 11A View Fig ). The cusp is elongated and distally inclined in labial/lingual views. The cutting edges are slightly sigmoidal in profile view.A small, sub-triangular and divergent cusplet is present on either side of the cusp. The root is asymmetrical in labial/ lingual views, with the mesial lobe being longer and more slender than the distal lobe. The extremities of both lobes form an acute angle. A rather symmetrical basal view characterises the root, with a triangular lingual protuberance, well demarcated from the rest of the root. The basal face of the root is concave in profile view.
Upper lateroposterior tooth files: Four teeth included in the study are regarded as upper lateroposterior teeth ( Fig. 11B–E View Fig ). They are most likely derived from the mid- to posterior part of the inferred upper lateroposterior hollow. They range in height from 8–14 mm. The cusp is more-or-less strongly distally curved and broader in the larger teeth than it is in the smaller ones. The labial side of the tooth is concave in profile in all teeth. The cusplets are relatively large and upright or slightly divergent. The root is asymmetrical in all teeth with the mesial lobe larger than the distal lobe. The median indentation of the basal edge of the root is rather small and tightly curved in the two largest teeth. The lingual protuberance is very small in basal view but well demarcated except in the largest tooth, in which this part of the root is somewhat abraded ( Fig. 11B View Fig 3 View Fig ).
First lower anterior tooth file: An incomplete tooth is assigned to the a1 position ( Fig. 11F View Fig ). One cusplet and the tip of the cusp are broken off. The breakage surfaces are both fresh looking, without any signs of feeding related, subsequent abrasion. This indicates that the tooth was damaged during extraction from the stratum. As preserved, it measures 24.5 mm in height. The original height is estimated to have been 27–29 mm. The narrow cusp is very slightly inclined in labial/lingual views and labially curved in profile view. The base of the crown forms a rather acute angle medially on the labial side. The remaining cusplet is almost identical in morphology to those of the A2 tooth, displaying a sub-triangular shape with slightly convex cutting edges. The root is nearly perfectly symmetrical, both in labial/lingual and basal views. As in the a1 of C. borealis ( Fig. 10A View Fig ), and unlike upper anterior teeth, the lingual protuberance is not well demarcated in basal view ( Fig. 11F View Fig 4 View Fig ). The basal edge of the root is V-shaped.
Lower lateroposterior tooth file: A single, 11 mm high tooth is referred to the inferred lower lateroposterior hollow Fig. 11G View Fig ; holotype). The cusp is triangular and moderately distally inclined. The labial face of the cusp is wrinkled medially in the basal part (a common feature in species of the C. borealis group). A sub-triangular, divergent cusplet with convex edges is situated on either side of the cusp. The labial side of the tooth is very slightly concave in profile view. The root is deep and strongly asymmetrical in lingual/ labial views with the mesial lobe being much larger than is the distal lobe. The outer edges of the root are straight and vertical and the median indentation of the basal edge is small and U-shaped.
Remarks.—Teeth of C. gertericorum sp. nov. most closely resemble those of C. borealis and C. ewelli sp. nov. The differences between the former two species are outlined above in the description of C. borealis . The assigned A2 of C. gertericorum sp. nov. ( Fig. 11A View Fig ) differs from the corresponding teeth in C. ewelli sp. nov. ( Fig. 12B, C) by its considerably more labiolingually compressed cusp. Upper lateroposterior teeth of the former differ from similarly sized ones of C. ewelli sp. nov. by their broader cusp ( Figs. 11C View Fig 3 View Fig , 12D 3 View Fig ), more concave labial profile and narrower, more tightly curved median indentation of the basal edge of the root.
Although the anterior teeth are markedly different in C. gertericorum sp. nov. and the co-existing C. appendiculata and C. deschutteri sp. nov., lateroposterior teeth may have overlapping crown morphology in the three species. Many of the examined laterposterior teeth are difficult to identify at species level, as the highly diagnostic root is rarely preserved intact. The lateroposterior teeth of the three species described and illustrated herein do not represent the average state of preservation in the early Turonian Tourtia de Bettrechies but comprise handpicked, unusually well-preserved examples.
Geographic and stratigraphic range.— Type locality and horizon only.
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