During the Neogene, a number of taxa began to increase rapidly in size, based on the fossil tooth evidence. Best known are the teeth of Carcharocles, but those of Cosmopolitodus, Hemipristis and Parotodus are other well-known examples. With the exception of Hemipristis and Cosmopolitodus (the lineage recognized today as Carcharodon), these megasized taxa disappeared, probably as a result of a cataclysmic decline in their prey. The teeth now referred to as Parotodus benedeni can be traced back to the Late Oligocene growing in size up till their disappearance in the Late Pliocene. Unlike the others with cutting dentitions, Parotodus had inordinately enlarged root lobes and thick (labio-lingually) and distally-directed crowns -- a heavy-duty tearing design. The taxon's ecological niche is still unknown, but this dentition-design, with such enlarged teeth, suggests it was different from its contemporaries.
The fossil record suggests it had a circumglobal presence in temperate/sub-tropical waters, but from the general rarity of the teeth, it can be surmised to have had an off-shore, pelagic lifestyle. Kent (1999) using published TL-from teeth algorithms (not fully accepted by this author) calculated P. benedeni body lengths of 4.7 (based on enamel height) to 7.6m (based on assumed jaw dimensions). Unless the family relationship can be established, applying either of these algorithms would seem foolhardy to me.
Summary of the published record
In viewing the available literature, certain papers appear more relevant than others. The summary below hopefully provides an adequate overview. (It does include some items which initially might not appear relevant.)
Agassiz (1844:281) erects Oxyrhina quadrans and depicts these specimens in plate 37, fig 1 & 2 (See figs. & below). These specimens lack roots and the crown itself is damaged on the second.
Agassiz described2 the [lateral] teeth as, "the morphology of this species is very characteristic, highly curved, and its sharp tip gives these teeth more or less the outline of a Galeocerdo. ...some posterior hastalis ... do resemble these teeth but this similarity isn't that striking ....Another important characteristic is the convex labial face, instead of being flat or concave (fig. 1a & 2b). The base of the enamel is slightly undulated on the labial face (fig.2),"
Regarding the anteriors. "other teeth can also be attributed to this species: these are similarly-sized, short and large, but with upright cusps...and also have a slightly convex labial face."
He reported these from the Tertiary of the Rhine Valley, Germany.3
Le Hon (1871: 6) based his new species Oxyrhina benedenii on a lower first anterior tooth from the "Pliocene", later determined to be middle Miocene,4 of Antwerp, Belgium (See figure below).
He wrote:2 "Species with an enormous thickness resembling the Cretaceous Oxyrhina crassidens of Dixon. The dental band is very broad and pronounced as in all teeth with a thick root. The crown is more or less inclined and the curved or hooked teeth, having the same characteristics, appear to belong to the same animal. Oxyrhina quadrans, Agass, seems to fit well with these curved teeth, which form the posterior part of the jaw of the herein described species."
In this paper5, he also erected Anotodus agassizii and illustrated three specimens collected in or around Antwerp without noting a type [assumed to be the first depicted from two perspectives; see fig. below]. In describing "the generic name Anotodus" he made several comments:2 summarized as:
- Similar to Otodus (macrotus, apiculatus and rupeliensis) with a prominent lingual dental band and no cusplets.
- The most striking characteristic is the labial [face] overhanging the root and the large depression underneath. This is never observed on another species.
- The tip of the crown, unlike Oxyrhina, is always rounded. The crown is, thin in the middle, thick at the base, sometimes erect but mostly distally inclined.
- Agassiz figured, under the name of Oxyrhina retroflexa, a mutilated tooth that might belong to this genus. Besides the absence of cusplets, we can't see any similarity between our dozens of teeth and the genus Oxyrhina and thus we ask the eminent palaeontologist to accept the creation of this species.
[JB comment: Amazing how in a few short paragraphs, Le Hon acknowledged his attempt to hijack two of Agassiz's taxa.]
Davis (1888:26-27) described as Oxyrhina vonhaastii an associated tooth-set set (in matrix) from New Zealand (Paper not available, Chapman 1918 included this specimen as Fig 1 of Plate IV; see Fig. above).
Woodward (1889:385). I haven't seen this paper, but Leriche (1906: 302) referred to it and noted that the author thought that the O. quadrans specimens should be considered posterio-laterals and be placed in O. hastalis.
Eastman (1894:190) synonymized both O. quadrans and O. retroflexa AGASSIZ 1843 with O. hastalis.
Chapman & Pritchard (1904:282) synonymized Davis' Oxyrhina vonhaastii with O. retroflexa and noted that all of the New Zealand examples were from the Oamaru Formation (Oligocene) of New Zealand.
Leriche (1906:302) synonymized O. quadrans with O. retroflexus . In addition,
he synonymized le Hon's two Anotodus upper teeth (that would be the second & third in outline only) with O. retroflexa.
Leriche (1910: plate XVI) provided a series of multi-perspective tooth images for multiple positions of Oxyrhina benedeni from the Rupelian (Early Oligocene) of Belgium. (See fig. above). In this proposed series of benedeni teeth, two of the upper laterals have cusplets.
Chapman (1918; 18) now reports as Isurus retroflexus the Davis material (included as Fig 2 of Plate IV, see Fig. above).. He goes on to note a second associated set which is likely the one depicted in Kemp (1991).
Menner (1928: 337) described the new species Otodus pavlovi for teeth from the Ypresian6 (Early Eocene) of western Kazakhstan. The teeth were briefly described as small, bearing lateral cusplets and a well-developed root. Zhelezko & Kozlov (1999:157) moved pavlovi to Parotodus. Collectors have attributed similar teeth from the London Clay to this taxon, however this has never been published.
Van de Geyn (1937) attributed benedeni (tooth-design) to Isurus.
Glikman (1964:103) erected the Family , in which he included:
Otodus, Palaeocarcharodon and Megaselachus.
Under RICHARDSON 1846 he included (pp 102-103):
(Glikman makes no mention of pavlovi or benedeni in the paper.)
Von der Hocht (1978b) placed benedeni in Anotodus LE HON 1871.
Herman (1979:370) wrote that, to him, it didn't seem possible to include "Oxyrhina" benedeni in the genus Anotodus7, ("This species might represent another group, isolated in time and space"). However, he deemed both Anotodus and O. benedeni as belonging in (he makes no mention of pavlovi).
Cappetta (1980) erected Parotodus with LeHon's O. benedeni as its type species (formerly attributed to Oxyrhinus, Isurus and Anotodus) and most other authors have employed this generic name for the last thirty years, He noted the possible presence of cusplets in the description and included Parotodus in ; no mention was made of Menner's Otodus pavlovi. [JB: As will be noted below, there is not consensus that a single species is represented by Leriche's figures.]
Cappetta (1987:104) summarized the Parotodus tooth-design and included the genus in the , and reported it from the Oligocene-Pliocene of Western Africa, Europe and North America, the earlier ones of which may have lateral cusplets. He deemed it a pelagic taxon, never very abundant, with teeth that thicken and increase in size over time. He mentions only P. benedeni in the genus.
Kemp (1991: 514-15) reported Isurus benedeni for the Middle Miocene of Australia. In addition, he depicts (pl. 32) a group (n=30) of associated Early Miocene benedeni teeth which includes a "parasymphyseal"-type (A0) tooth-design.
Yabe & Hirayama (1998: 47-48) reported Parotodus benedeni from the Senhata Fm (Upper Miocene) of Japan. They noted that in Japan, this tooth-design had been described by Hatai et al. (1974) as Isurus moniwaensis; and, that Kuga (1985) synonymized it with benedeni, but under his newly created genus - Uyenoa.
Zhelezko & Kozlov (1999b:156-57) erected the species Parotodus mangyshlakensis for cuspleted Parotodus-like teeth from the Middle/Late Eocene Schorym Formation in Mangyshlak, Kazakhstan. They described them as larger and with a broader, more massive, crown than P. pavlovi and less so than P. benedeni; they considered it a transitional form between the two.8
Siverson (1999), based on material from the Cenomanian of Australia, described a new genus (Cardabiodon) and species (ricki) and erected a new Family for it. To this family he moved Parotodus. He considered the defining characteristics (tooth related) for this family to be the presence of four upper & lower anterior tooth positions (sensu teeth emanating from the anterior hollow).
The 2nd-4th upper positions were all distally inclined and the fourth lower (LA4) significantly reduced in size (relative to the lateroposteriors); the teeth lack a median root groove and the lower lateroposteriors are enlarged relative to other tooth-positions (Siverson & Lindgren 2005: 307). [JB: Siverson may have defined Cardabiodon well, but never presented a good argument (in my opinion) to move Parotodus to this new family.9]
Kent & Powell (1999) reported on a large associated set10 (n=114) of P. benedeni teeth from Lee Creek. They proposed/argued:
- The recovered tooth-group represented an associated dentition-set
- These specimens could be attributed to the Lower Yorktown (Unit 1/2)
- The teeth could be arranged (see Fig. below) to provide better insight into Parotodus dentition design
- The Parotodus tooth-design should be placed with the .
They went on to note other associated benedeni tooth-sets, including one from the Oligocene of New Zealand attributed to Oxyrhina vonhaastii by Davis (1888:26-27)and another from Japan. They also referred to teeth in private collections reaching 7.2 cm in height.
Purdy (2001:110-113) included P. benedenii in the , and reported teeth recovered from the Yorktown (Units 1-2, Early Pliocene) Formation of NC. They described the tooth design and proposed a partial composite dentition (see Fig. above). The authors rejected Leriche's (1910: plate 16, figures 5 and 6) teeth with cusplets as benedeni (Fig. above) but rather as Lamana rupeliensis
Siverson & Lindgren (2005: 307) shed more light (or should I say shadows) on this topic while discussing Late Cretaceous sharks from Montana. Their arguments were perfectly clear to me, but their comments regarding Parotodus and include:
- It is difficult to prove that Parotodus is a cardabiodontid because of the lengthy gap (Late Turonian to Early Rupelian) in the fossil record).
- Teeth attributed to Parotodus mangyshlakensis may represent a non-Parotodus taxon and that Leriche's (1910: plate 16) illustrated P. benedini specimens may be tainted (by a "heterogeneous mix") with the mangyshlakensis tooth-design (based on the root's lingual protuberance and lateral tooth cusplets).
- The Early Eocene tooth-design from Morocco referred to as "Parotodus sp" may be erroneously placed in that genus, based on apicobasal neck width.
Cappetta (2006) placed Anotodus in the and Parotodus (including benedeni & pavlovi) in .
Regarding Oxyrhina quadrans, he referred them to the Miocene of Germany, noted they compared well with P. benedeni and that strictly applying the rules of priority would make benedeni junior to quadrans. However he noted,2 "As usage has established the first appellation, it would be better to preserve this name for nomenclatural stability. [Syn. of Parotodus benedenii (Le Hon, 1871a)] Otodontidae]."
There are likely additional useful references, but the above provides a snapshot of the thinking of fossil shark specialists over time.
So, what do we have?
It would now appear that Le Hon successfully usurped quadrans from Agassiz but failed with retroflexus. Why the following generation allowed it is unknown, but as Cappetta (2006) suggests, it's a fait accompli -- live with it.
There seems to be broad acceptance of the Oligo-Pliocene teeth without cusplets as Parotodus benedeni11. This consensus of both genus and species falls apart when the tooth-design is extended to include teeth with cusplets, including those depicted by Leriche (Fig. above). For the purposes of this webpage, only the consensus definition of Parotodus benedeni will be discussed. The other teeth (pavlovi and mangyshlakensis, including Leriche's Figs. 5 & 6) will be referred to "Parotodus" (in quotes) to indicate their unresolved status. The appropriate family is equally problematic, particularly when the Kent & Powell (1999) reconstruction is compared with those of the , , and ; each option has certain valid aspects. For this reason, the website will include P. benedeni as Family: incertae sedis.
Under most circumstances, Parotodus benedeni teeth can be readily differentiated from other tooth-designs by their distally directed triangular crown (in most positions) and massive proportions, The crown is thick (D-shaped in cross-section), smooth, has a complete cutting edge and large, well defined neck. The roots are massive (more so in lowers), with well defined lobes and a strong lingual protuberance bearing small scattered pores (no well defined groove or central pore). Small Neogene specimens may be confused (at least for me) with large non-serrate specimens of Alopias grandis. The accompanying images (below) provide a good example of positional variations.
The benchmark for this taxon's dentition design is certainly Kent & Powell (1999). The tooth-set is large, the stratigraphy known, the association well-argued, the methods clearly defined and in most cases the conclusions reasonable12. In broad terms (when viewed laterally), the uppers are erect or labially recurved, while the lowers tend to be more lingually directed. Kent & Powell concluded the formula was - upper: A=2, I=1, L=7, P-4; lower A=3, L=6, P-4. As elasmo.com follows Siverson (1999), the upper "intermediate" is here considered the third upper anterior and be added to the anterior count and the lateroposteriors merged -- the comparative basis would therefore be uA=3, uLP=11, lA=3, lLP=10. This formula has 2 or 3 more lateral files than Otodus and 3 or 4 less than Cardabiodon. The robust distally-directed crowns would suggest a powerful tearing dentition.
Lastly, the Kemp (1991) associated set included the A0 (aka parasymphyseal) tooth position. As this is the only documented presence for this file, it is currently viewed (by this website) as sometimes present (as seen in the Otodus-Carcharocles lineage).
Thoughts on those Eocene teeth
One's take on the genus of the Eocene teeth is largely influenced by an underlying boolean decision of the P. benedeni tooth-design -- otodontid or not. If thinking of benedeni to be the former, the Eocene examples make an excellent transitional form -- combining robust otodontid-like roots (sensu Cretalamna & Otodus) and cusplets, but with a thick (D-shaped) cusp. However, if one rejects the notion of P. benedeni being an otodontid, then the lack of cusplets, thick cusp and more importantly root and dentition designs serve as excellent evidence to separate the P. benedeni from that Eocene design. Personally, I tend to side with Siverson & Lindgren (2005) and consider the Eocene teeth ododontid and unrelated to P. benedeni. Unlike Siverson and based on dentition design, I don't consider P. benedeni a cardabiodontid, but more likely an alopiid as suggested by Herman (1979)13.
I thank Lutz Andres, Bill Heim, Rick Johnson, René Kindlimann, Bill Moriss, Pat Young and particularly Steve Alter for providing the large group of reference images on this page; Mikael Siverson for his patience in explaining the underlying arguments for his Cardabiodon-Parotodus hypothesis and Pieter De Schutter for the European images, translations and tracking down some of the less common references employed. Earl Manning provided a meticulous review, lively debate, helped hone the wording and pointed out weaknesses or gaps that needed to be addressed.
||A variety of opinions on the appropriate family of the genus are discussed here.|
||Translation provided by Pieter de Schutter.|
In discussing the type specimen (Natural Museum of Neuchatel, Switzerland), René Kindlimann (pers. com 2008) noted: "Nothing is known about the Locality. It is said to come from the Miocene / Oligocene somewhere in Germany. But there is no locality close to Mayence Basin known to yield Miocene fossils, except farther north (Niederheinische Bucht etc.). And I know that teeth of P. benedeni have been found several times by local collectors within the Mayence Basin (Oligocene) during the last years.|
I cannot say if this tooth really comes from the Oligocene. Its preservation is in fact quite different from typical oligocene finds (sharkteeth), which are normally more or less complete and in shiny condition. This tooth is not!"
||Leriche (1926:395) noted, "that the Pliocene layers Le Hon wrote about are in fact the middle Miocene Antwerp Sands and what he called Miocene are in reality Oligocene sediments." (Pieter De Schutter translation) |
||According to De Schutter (pers. com. Jun 2008), Le Hon was preparing a large work about these teeth; he mentioned that he already prepared dentition sets of Oxyrhina trigonodon, O. hastalis, Lamna (Odontaspis) vorax and Carcharodon escheri. He was working on reconstructing the tooth set of Oxyrhina crassa and was hoping to find the complete jaw of Carcharodon megalodon. This is partly written in Leriche (1926:375):"Le Hon died in 1872, a little after the publication of his preliminary work, without being able to complete the definitive work he announced."|
||The text seemed to suggest Palaeocene, but Zhelezko & Kozlov (1999b:157) refers to it as Ypresian.|
||Herman included in Anotodus: Oxyrhina retroflexa (= Oxyrhina complanata SISMONDA 1849; Anotodus agassizii; & Oxyrhina crassa PRIEM 1913) [type] and A. leeensis (WARD 1978) which were considered by him to be alopiids. Cappetta (2006) appears to have continued this thread of logic.|
Having reconstructed a tooth-set from lower Miocene retroflexus teeth and compared/contrasted them with extant I. paucus jaws, an alopiid association of retroflexus is difficult to accept.
||Commenting on "P." mangyshlak. Siverson (pers. com. July 2008) noted: "Very distinctive lower anterior teeth with a huge lingual protuberance of the root. The lateroposteriors are collectively much closer to Otodus/Cretalamna than the Eocene teeth you illustrated
[Figs. - ]."|
||Siverson (pers. com. June 2008) notes:
"Teeth from very young Cardabiodon venator would be almost indistinguishable from Parotodus if you enlarged them (Siverson & Lindgren, 2005, fig. 3G).... Based on this one could argue that the fossil record indicates that Parotodus might be a pedomorphic Cardabiodon.
There are more similarities tooth and dentition-wise between Cardabiodon and Parotodus than there are between the latter and Otodus. Kent and Powell's LA3 looks a lot like the inferred LA3 in C. ricki. In fact it is a most unusual tooth design.
The dentition of Cardabiodon is broadly speaking of the Alopias-type with distally directed cusps on the upper anterior teeth and moderate-tooth size relative to the overall body size."
||In 1992, Clyde Swindel found a small group (n=6) of Parotodus teeth in Lee Creek tailings and suspected that these numerous 'rare' teeth appearing in close proximity might represent an associated set. A group of volunteers would eventually recover 114 specimens from this small area of basal Yorktown (Early Pliocene) tailings.|
||Depending on the author, the species is spelled benedeni, or as erected, benedenii. For those into nomenclature details, I'm sure this is a very important point; I take a 'who cares' attitude and (for now) go with the published consensus (one 'i').|
||The conclusions on dentition-design are more problematic. Working with Hubbell associated tooth-sets, 75 teeth seems to be a good breakpoint for the reliability of the group. This Parotodus tooth-set exceeds this minimum count and includes a variety of positional tooth-developments. With that said, a missing tooth-position raises a red flag. When a tooth-position is missing (i.e. UA3), there is usually an underlying cause:
Tooth-size -- A collecting bias may be present.
Erosional bias -- A particular portion of the tooth-set eroded differently after deposition (all posterior RH files missing, lowers more poorly represented or most anterior files less well represented.|
In the case of this reconstruction, missing tooth positions as identified by the authors are rather haphazard. They argue for an "Intermediate" (here A3) position but have no teeth and represent this position by a small fragment. The posterior-most tooth is not present in the collection, yet they add that position to the dentition-set. They have no example of their URL6 from one quadrate and no uLL3 from the other.
It is important to note that the tooth-design (UA3) hypothesized by Kent & Powell is present in the Purdy et al. (2001) composite reconstruction and in the above imaged teeth. The question raised is whether that design is universal in all Parotodus dentitions or a particular variation (i.e., sexual or individual dimorphism).
Interestingly, if one removes the positional discrepancies as noted above, the resulting tooth formula compares better with that of Otodus, better validating their systematic conclusion.
The documentation of this associated tooth-set is very important and should not be trivialized. However, the tooth-formula needs to be confirmed with collateral evidence. Not having studied the tooth-set, I can't propose an alternate arrangement (or verify this one), only suggest that it might be questioned.
||Siverson (pers com Jul 2008) comments, "Obviously something in the Eocene must be a Parotodus-line species and right now those Moroccan Ypresian examples (which are clearly not "P". mangyshlakensis, unless you have been very selective in your choices of specimens) carry more credibility than my C. venator-Parotodus idea. At the time I had a look at David's [Ward] Moroccan specimens I thought the neck was too thin but then again Otodus increased the width of the neck on lateroposterior teeth quite rapidly in the Paleocene. It is not very wide at all in Danian examples."|
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