P. De Schutter © 2010
During the Cretaceous, neoselachians diversified rapidly (UNDERWOOD, 2006). Particularly the middle part of the Cretaceous was a time of high diversity and rapid rates of dental evolution in lamniform sharks (SIVERSON & LINDGREN, 2005). However, the arrangement of these taxa into families is far from understood and differs among researchers, especially between morphological (e.g. COMPAGNO, 1990; SHIRAI, 1996; SHIMADA, 2005) and molecular studies (e.g. MARTIN & NAYLOR, 1997; NAYLOR ET AL., 1997).

The Cretoxyrhinidae sensu CAPPETTA (1987) included the Cretaceous genera Cretalamna, Cretodus, Cretoxyrhina, Leptostyrax, Paraisurus, Pseudoisurus and Protolamna. SIVERSON (1992, 1996) tentatively accepted this classification and added Archaeolamna to the Cretoxyrhinidae. Later, SIVERSON (1999) considered Cretoxyrhinidae to be monotypic and restricted it to Cretoxyrhina. Taxa, previously assigned to Cretoxyrhinidae, should be placed into other suprageneric taxa. As only skeletal material and associated dentitions can help in solving the position of most fossil lamniforms (SIVERSON, 1999; KRIWET, 2006), some genera previously included in the Cretoxyrhinidae are not yet attributed to any nominal family.

Numerous large lamniform teeth are recovered from Albian to Maastrichtian strata in Belgium and northern France, assigned to the genera Cretalamna, Archaeolamna, Cretoxyrhina, Cretodus, Dwardius, Paraisurus, Cardabiodon and Protolamna. This webpage has the purpose to serve as an aid in the identification of these teeth.
Glickman 1958
Cretoxyrhina mantelli (Agassiz, 1843)
[Cenomanian-Turonian & Campanian]
Kriwet, Klug, Canudo & Cuenca-Bescos 2008
Protolamna borodini (Cappetta & Case 1975)
[Campanian & Maastrichtian]
Protolamna compressidens (Herman, 1977)
Protolamna sp. [Albian]
Glickman 1964
Cretalamna appendiculata (Agassiz, 1843) [Cenom.-Turonian]
Cretalamna deschutteri Siverson et al., in press   [Cenom.-Turonian]
Cretalamna gertericorum Siverson et al., in press   [Cenom.-Turonian]
Cretalamna borealis (Priem, 1897) [Campanian]
Cretalamna sarcoportheta Siverson et al., in press   [Campanian]
Cretalamna lata (Agassiz, 1843) [Maastrichtian]
Siverson 1999
Cardabiodon aff. ricki Siverson, 1999  
Cardabiodon venator Siverson & Lindgren, 2005 [Cenomanian-Turonian]
Underwood & Cumbaa 2010
Archaeolamna aff. haigi Siverson, 1996 [Albian]
Archaeolamna ex gr. kopingensis (Davis, 1890) [Campanian & Maastrichtian]
Cretodus semiplicatus (Münster in Agassiz 1843) [Cenomanian-Turonian]
Incertae sedis 1
Paraisurus macrorhizus (Pictet & Campiche, 1858) [Albian]
Incertae sedis 2
Dwardius siversoni (Zhelezko, 2000) [Albian]
Dwardius woodwardi (Herman, 1977)  
? SERRATOLAMNIDAE Landemaine 1991
- possibly otodontid (Siverson, 1999: 61) -
Serratolamna serrata (Agassiz 1843) [Maastrichtian]
Leptostyrax and Protolamna are reassigned to the Eoptolamnidae (KRIWET ET AL., 2008), a family created for the Barremian genus Eoptolamna and considered as one of the oldest fossil lamniform families.

An important difference to distinguish teeth of Leptostyrax from teeth of Protolamna is the lingual crown ornamentation, which is very faint and restricted to the crown base in Leptostyrax, whereas it comprises long folds reaching up to the cusp tip in Protolamna (CUNY ET AL., 2004; KRIWET ET AL., 2008).
An exception appears to be Protolamna compressidens (HERMAN, 1977), which displays a nearly smooth crown surface (HERMAN, 1977: 193).
The genus Pseudoisurus GLÜCKMAN 1957 is poorly defined (HERMAN, 1977; CAPPETTA, 1987) and is considered a nomen dubium (SIVERSON, 1999: 57). In contradiction, ZHELEZKO (2000) regarded Cretoxyrhina as a junior synonym of Pseudoisurus and attributed 5 species to Pseudoisurus, assuming a successive evolutionary lineage with a gradual decrease of cusplets in teeth from the Albian (P. siversoni) to Campanian (P. mantelli), and in addition, a gradual transition from a tearing-cutting dentition to a cutting type dentition.
SIVERSON (1999) created the genera Cardabiodon and Dwardius for the teeth previously attributed to Pseudoisurus.
Cardabiodon SIVERSON, 1999
Cardabiodon ricki SIVERSON, 1999 - Cenomanian
Cardabiodon venator SIVERSON & LINDGREN, 2005 - Turonian
This genus' dentition consists of 4 upper and lower anterior teeth. The first upper anterior tooth is reduced in size. The 2nd to 4th upper anterior tooth and the upper and lower lateroposterior teeth are distally inclined, more than seen in Dwardius. The lateroposterior teeth are greatly enlarged. The largest lower anterior is exceeded in size by the first and second lower lateroposterior tooth, while in Cretoxyrhina, the largest lower anterior is much larger in size than the largest lower lateroposterior tooth. Distally situated lateroposterior teeth are labio-lingually compressed.

Dwardius SIVERSON, 1999
Dwardius siversoni (ZHELEZKO, 2000) - Albian
Dwardius woodwardi (HERMAN, 1977) - Cenomanian

SIVERSON (1999) created a genus of uncertain familial affiliations, Dwardius, for Cenomanian teeth previously referred to as Cretolamna woodwardi HERMAN, 1977. This species was originally described by HERMAN (1977: 207-208) using an associated group of teeth recovered from the English Chalk and figured in WOODWARD (1911) as Lamna appendiculata. These teeth can not be included in the genus Cretalamna due to its very different root morphology (see SIVERSON, 1992: 530; 1996: 830). In Dwardius, anterior teeth have a more or less straight cusp, which, in contrast to Cardabiodon, are markedly enlarged relative to the mesially situated lateroposterior teeth.
Type series of Dwardius woodwardi (HERMAN, 1977) in WOODWARD (1911): p. 207, fig. 64
Dwardius siversoni
The Cretoxyrhinidae GLÜCKMAN 1958 sensu SIVERSON (1999) only include Cretoxyrhina mantelli (AGASSIZ, 1843), ranging from late Albian to early Campanian. This species’ dentition has only three upper and lower anterior teeth. For a good description and figuration, see WELTON & FARISH (1993), SHIMADA (1997) and the elasmo.com/Cretoxyrhina genus page.
During the latest Albian to middle Turonian interval, Cretoxyrhina and Cardabiodon were in the process of loosing the cusplets on their teeth, starting in the anterior files. This process was well under way by the latest Albian in Cretoxyrhina and by the middle Cenomanian in Cardabiodon. In early populations of Cretoxyrhina (Albian-Cenomanian), cusplets may be present on lateral and posterior teeth, while the cusplets become reduced in lateral files in later populations (Turonian-Campanian).
Cretalamna GLICKMAN 1958
Latest Albian to Early Eocene (CAPPETTA, 1987)
Glickman’s (1958) original spelling of the taxon was Cretalamna, being repeatedly misspelled as Cretolamna in the subsequent literature (see SIVERSON, 1999; SHIMADA, 2007).
HERMAN (1977: 214) recognised three varieties of Cretalamna:

Cretalamna appendiculata var. appendiculata [Cenomanian-Late Campanian]; cusplets large and erect on lateral teeth, but reduced and slightly diverging on anterior teeth.

Cretalamna appendiculata var. lata [Late Campanian-Late Maastrichtian]; a very typical morphology with anterior teeth that display a wide and low cusp.

Cretalamna appendiculata var. pachyrhiza [Late Campanian- Early Palaeocene]; acquiring a more massive root, this form is close to Otodus. Lateral teeth of this variety have large and strongly diverging cusplets.

Archaeolamna SIVERSON, 1992

Globally, the dentition of Archaeolamna resembles that of odontaspidids, but the lack of a nutrient groove demonstrates its lamnid affinity (SIVERSON, 1992: 530). The dental formula differs from that of all other known Cretaceous lamniforms in possessing lower symphyseal, upper symphyseal and intermediate teeth, associated with three large upper anterior teeth (UNDERWOOD & CUMBAA, 2010). The most distal lateroposterior teeth are much reduced in size and exhibit strong labial folds on the crown. Anterior and lateroposterior teeth of this species have well-developed cusplets during its entire temporal range (Albian-Maastrichtian), which are well-separated from the base of the cusp.

Cretodus SOKOLOV 1965
Cretodus semiplicatus (Münster in Agassiz, 1843) - Albian to Cenomanian
Cretodus crassidens (Dixon, 1850) - Turonian
The evolution of this genus involves a decrease in the lingual folds and a tendency to lose the cusplets (CAPPETTA, 1987). SCHWIMMER ET AL. (2002) suggest that crassidens is conspecific with semiplicatus.
The presence or absence of symphyseal teeth is important for grouping fossil lamniform genera into families. Symphyseal teeth, small teeth formed on the symphyseal bars and in the groove between the bars (sensu SIVERSON 1999), are only present in Cretoxyrhina, Cretalamna, Cardabiodon, Archaeolamna and possibly Dwardius (SIVERSON, 1999; SHIMADA, 2007; UNDERWOOD & CUMBAA, 2010).
Examining associated dentitions, SIVERSON (1999) observed a single file of upper symphyseal teeth in Cardabiodon, while Cretoxyrhina possesses multiple files of upper symphyseals (SHIMADA, 1997; SIVERSON, 1999). SHIMADA (2007) observed 2 files of upper symphyseal teeth in Cretalamna.
Besides the size, symphyseal teeth of Cretalamna and Cretoxyrhina are very similar, but those of Cretoxyrhina exhibit a labial overhang of the root by the crown (SIVERSON, 1992).

BIDDLE, J.-P., 1993. Les Elasmobranches de l’Albien inférieur et moyen (Crétacé inférieur) de la Marne et de la Haute-Marne (France). In: Herman, J. & Van Waes, H. (eds), Elasmobranches et Stratigraphie. Service Géologique de Belgique, Professional Paper, 264: 191-239.

HERMAN, J., 1977. Les Sélaciens des terrains néocrétacés & paléocènes de Belgique & des contrées limitrophes. Eléments d'une biostratigraphie intercontinentale. Toelicht. Verhand. Geologische en Mijnkaarten van België, n°15, 450 pp.

KRIWET, J., KLUG, S., CANUDO, J.I. & CUENCA-BESCOS, G., 2008. A new Early Cretaceous lamniform shark: Eoptolamna eccentrolopha gen. et sp. nov. (Chondrichthyes, Neoselachii). Zoological Journal of the Linnean Society, 154: 278-290.

SHIMADA, K., 1997. Dentition of the Late Cretaceous lamniform shark, Cretoxyrhina mantelli, from the Niobrara Chalk of Kansas. Journal of Vertebrate Paleontology, 17(2): 269-279.

SHIMADA, K., 2007.
Skeletal and dental anatomy of lamniform shark, Cretalamna appendiculata, from Upper Cretaceous Niobrara Chalk of Kansas. Journal of Vertebrate Paleontology 27(3): 584–602.

SIVERSON, M., 1992. Biology, dental morphology and taxonomy of lamniform sharks from the Campanian of Kristianstad Basin, Sweden. Palaeontology 35(3): 519-554.

SIVERSON, M., 1996. Lamniform sharks of the mid Cretaceous Alinga Formation and Beedagong Claystone, Western Australia. Palaeontology 39(4): 813-849.

SIVERSON, M., 1999. A new large lamniform shark from the uppermost Gearle Siltstone (Cenomanian, Late Cretaceous) of Western Australia. Transactions of the Royal Society of Edinburgh: Earth Sciences, 90: 49-66.

SIVERSON, M. & LINDGREN, J., 2005. Late Cretaceous sharks Cretoxyrhina and Cardabiodon from Montana, USA. Acta Palaeontologica Polonica, 50(2): 301-314.

SIVERSON, M., LINDGREN, J., NEWBREY, M.G., CEDERSTRÖM, P. & COOK, T.D., 2013. Late Cretaceous (Cenomanian-Campanian) mid-palaeolatitude sharks of Cretalamna appendiculata type. Acta Palaeontologica Polonica, XX (X): xxx-xxx

SCHWIMMER, D.R., HOOKS, G.E. & JOHNSON, B., 2002. Revised taxonomy, age, and geographic range of the large lamniform shark Cretodus semiplicatus. Journal of Vertebrate Paleontology, 22(3): 704-707.

UNDERWOOD, C.J., 2006. Diversification of the Neoselachii (Chondrichthyes) during the Jurassic and Cretaceous. Palaeobiology, 32(2): 215-235.

UNDERWOOD, C.J. & CUMBAA, S.L., 2010. Chondrichthyans from a Cenomanian (Late Cretaceous) bonebed, Saskatchewan, Canada. Palaeontology, 53(4): 903-944.

WELTON, B. & FARISH, R., 1993. The collector’s guide to fossil sharks and rays from the Cretaceous of Texas. Before Time, Texas, 204 pp.

WOODWARD, A.S., 1902-1912. The Fossil Fishes of the English Chalk. Palaeontographical Society, London. 264 pp.