Order
LAMNIFORMES Berg,
1958
Family ODONTASPIDIDAE Müller & Henle, 1839 Carcharias cuspidata (Agassiz, 1843) © P. De Schutter - 2006 _________________________________________________________________________________________ |
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In Belgium, Carcharias
cuspidata is rarely found in the early Oligocene: at the
phosphoritic base of the Boom Clay (early Rupelian) and in the
Boom Clay itself (late Rupelian). In contrast, Carcharias
acutissima is by far the most frequently found larger species
in these deposits.
Associated tooth sets of Carcharocles angustidens, Cosmopolitodus flandricus, and Carcharias acutissima... were uncovered in the Belgian Boom Formation (Leriche, 1910), but unfortunately none of Carcharias cuspidata. In 1990 however, a unique associated tooth set was found in the Middle Oligocene of the Winterswijk region in the Netherlands (van den Bosch & Oosterink, 1991); unfortunately this set was never published in detail. In the German Mainzer basin Carcharias cuspidata is regularly found (von der Hocht, F., 1978; Reinecke et al, 2001), while it's the most common larger species (more than C. acutissima) in the Leipzig region (Freess, 1992). It also regularly occurs in the sandy French Stampian (= Rupelian) (Leriche, 1910). Agassiz (1843: 290 + pl.37a, fig.43-50) described the species Lamna cuspidata for the first time, using specimens from the Molasse suisse (the Miocene of Switzerland). Agassiz also noted that a series of teeth from Flonheim (Rupelian, Mainzer Basin, Germany) belong to the same species. The tooth Agassiz figured as n°47 is still accessible in the collection of the museum in Neufchatel, Switzerland, and appears to be composed of pieces from different specimens (pers. comm. von der Hocht 2006). Leriche (1910: plate XV) figured the different tooth positions using isolated specimens collected from the Boom Formation in Belgium. He figured almost identical teeth for both the UA1 and LA1 positions, half as large as the other corresponding anterior teeth, a compressed root and very tiny cusplets. The second lower anterior has a very thick protuberance and may be the largest tooth in the jaw. The upper jaw consisted of three (regular) anterior teeth. Leriche also figured (suspicious) intermediary teeth, similar in size as the above teeth. Extant odontaspids do have small intermediate teeth, but such teeth were not found in our sample Belgian Oligocene C. cuspidata teeth. However in the German Mainzer Basin this species is more common; intermediary teeth that can be attributed to C. cuspidata were found (see picture below). These teeth closely resemble those of C. taurus and Striatolamia. C. cuspidata first appears in the fossil record during the Priabonian, late Eocene; later it disperses widely (Malyshkina, 2004). This species survived into the Miocene (Cappetta, 1987). The teeth are large and robust. Carcharias cuspidata is the largest member of the Neogene Odontaspididae with Oligocene anterior teeth (in my collection) of 50mm in height. The crown is entirely smooth. The cutting edges are complete with some exceptions. Anterior teeth have relatively short root lobes and small, but sharp cusplets. The root is massive with a thick protuberance (can be very strong in lower anteriors) and a very large nutrient groove. Lateral teeth have a flatter root, more obtusely splayed root lobes and a strong nutrient groove. Upper lateral teeth are distally inclined while lower laterals are straighter or only slightly inclined. Typical for the lateral teeth is the diversity of the cusplets; being sharp and high, triangular, or low and serrated. Sometimes small serrations can be observed at the base of the cutting edge of the crown (as seen in Palaeohypotodus and Jaekelotodus). The cutting edge, which is complete, can form a (serrated) bridge with the cusplets: tiny cusplets connecting the crown's cutting edge with one broad and triangular cusplet. Sometimes the cusplets are no more than a prolongation of the cutting edge. Regularly they bend towards the crown. Agassiz (1843: 291 + pl.37a, fig.51-53) gave these typical lateral teeth the name Lamna denticulata. He noted however the similarity between denticulata and cuspidata and also that both species were found in the Oligocene and Miocene. Le Hon (1871: 5) already made the suggestion that Agassiz' Lamna denticulata most probably are teeth from the middle part of the upper jaw of Lamna cuspidata. At the base of the Rupelian in Belgium a large set of cuspidata teeth was collected in this limited faunal assemblage; this homogeneous set shows both Agassiz' cuspidata and denticulata types. In addition, Leriche (1910: plate XV, fig.1-21) figures both types as C. cuspidata. Where this species fits in the Carcharias evolution is not yet fully understood. It's probably the ancestor of Carcharias vorax (Le Hon, 1871), both having the same typical lateral teeth. All figured specimens, except for the last, were found in the Early Oligocene, Early Rupelian, Base Boom Clay (NP23) in Belgium. |
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First
upper anterior (UA1) H=24mm © F. Mollen - 2007 |
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2nd
upper anterior (UA2) H=30mm - Collection G. Marien - |
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3rd
upper anterior (UA3) H=35mm |
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3rd upper anterior (UA3) H=24mm |
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Lower
anterior |
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Lower anterior H=49mm |
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Lower
anterior H=35mm |
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Upper
lateral - H=26mm |
Upper
lateral - H=16mm |
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Lower
lateral H=15mm |
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Upper
posterior W=11mm |
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