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Very rare Cardabiodon tooth for trade

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indominus rex

Hello, today for trade I’d like to offer a very rare and big Russian Cardabiodon tooth. These are very rare sharks and you definitely don’t see them very often. For trade I’m looking for dinosaur material or large shark teeth (mainly Megalodon teeth, Mako teeth or Great White).

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MikaelS

Looks like Dwardius to me.

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indominus rex
29 minutes ago, MikaelS said:

Looks like Dwardius to me.

Yeah their teeth look very similar. But I asked some specialists and this is most likely Cardabiodon.

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siteseer
10 hours ago, indominus rex said:

Yeah their teeth look very similar. But I asked some specialists and this is most likely Cardabiodon.

 

How did those specialists distinguish the two genera?  I keep thinking of Cardabiodon and Dwardius as new but they turn 20 this year.  They were described by the same author, you know.

 

The other thing about Cardabiodon is that I'm not sure how it's pronounced.  I have always thought it was car-DAB-ee-oh-don (second syllable stressed) but a friend pronounces it as car-du-BI-oh-don (second syllable unstressed, third syllable stressed).  How do you pronounce it?

 

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siteseer
15 hours ago, Macrophyseter said:

Siverson (1999), which erected both genera, stated the differences in this quote-

 

 "Dental differences between Dwardius and Cardabiodon gen. nov. include: (1) the anterior teeth are markedly enlarged relative to the anteriorly situated lateroposterior teeth in Dwardius (see Woodward 1894, pi. 6, fig. 2), but not in Cardabiodon (Fig. 5); (2) the second to fourth upper anterior teeth have a markedly distally directed cusp in Cardabiodon. In Dwardius, anterior teeth appear to have a more or less straight cusp (see Woodward 1894, pi. 5, fig. 25a?, d, e, n?; pi. 6, fig. 2b?, d, f); (3) the teeth of the lateroposterior files in both the upper and lower jaws have a more distally directed cusp in Cardabiodon than in Dwardius; (4) distally situated lateroposterior teeth are more compressed labiolingually in Cardabiodon than they are in Dwardius, which has unusually stocky commissural teeth."

 

 

At least one study (Underwood et al., 2011) considered Cardabiodon and Dwardius to be synonymous and their differences merely significant genetic divergence. Siverson et al. (2013) responded to this by noting the evolutionary trends of the two genera which I believe could imply a refutation-

 

"Underwood et al. (2011) implied that Cardabiodon and Dwardius are synonymous but the differential characters outlined above indicate significant genetic divergence. The enlargement of the anterior teeth in D. woodwardi is more pronounced than in any other non-odontaspidid/mitsukurinid lamniform of Cretaceous age examined by us. Lateroposterior teeth from very young individuals are particularly different in later (latest Cenomanian to mid-Turonian) populations of the two genera; Archaeolamna-like in Dwardius but Alopias/Parotodus-like in Cardabiodon (Siverson & Lindgren 2005, fig. 3F, G). Cardabiodon was at a rather advanced stage of cusplet-reduction (especially in small juveniles) by the time it disappears from the fossil record (Siverson & Lindgren 2005, figs 3F, G, 4), whereas Dwardius evolved an opposite pattern, developing larger cusplets (especially in anterior files) towards the end of its temporal range (Fig. 3)."

 

And that same author, who also remains the lead researcher in both genera, also made that post above suggesting that the tooth for sale might actually be a Dwardius ;)

 

Siverson pronounces it as "car-da-BI-ah-don" (At least that's how he pronounced it at his talks at the Royal Tyrrel Museum). The genus literally means "tooth from Cardabia" after the cattle station of the same name that owned the land the C. ricki holotype was discovered from.

I believe that it's possible that he spelled the genus with an o instead of an a in order to correctly spell the root -odon.

 

 

Hi Macrophyseter,

 

Thanks for the quotes from the paper which may benefit many here.  I copied that paper not long after it was published back when the USGS had a library.  I wanted to know how the specialists who advised Indominus Rex compared them.  I am aware who MikaelS is.  I was just gently pushing Indominus in that direction.  Thanks for the note on the pronunciation.

 

Jess

 

 

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MikaelS

The fully prepared paratype dentition of Dwardius woodwardi is actually here at the WA Museum in Perth (on loan from the NH museum in London). I have not yet had time to publish on it but that is certainly my intention. There are indeed many similarities between D. woodwardi and C. ricki and because of this I am referring both to the same family these days (the Cardabiodontidae). They seem to have had a similar number of tooth-files (16ish) but the anterior teeth differs considerably. In the holotype dentition of C. ricki the height ratio between the tallest anterior and the tallest non-anterior tooth is about 1:1. In the paratype dentition of D. woodwardi the ratio is just over 1.5:1. From a distance the dentition of Dwardius would have looked a bit like that of a mako but with cusplets (both have greatly enlarged anteriors).

 

The most updated discussion outlining the dental differences between the two genera, but more specifically discussing nominal species of Dwardius, is that of Siversson & Machalski 2017 (Alcheringa).

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MikaelS
On 3/12/2019 at 12:55 PM, Macrophyseter said:

 

 

At least one study (Underwood et al., 2011) considered Cardabiodon and Dwardius to be synonymous and their differences merely significant genetic divergence. Siverson et al. (2013) responded to this by noting the evolutionary trends of the two genera which I believe could imply a refutation-

 

 

Cardabiodon and Dwardius are dentally considerably more different from each other than are the two modern species of Isurus (and Lamna) but could be regarded congeneric if you used modern Alopias as a template for intrageneric variation. This is based on the dentition only. Work is in progress describing numerous, extremely well-preserved vertebral centra that most likely belonged to Dwardius (Newbrey, myself and others). Overall there is plenty of work in the pipeline for cardabiodontids as we begin to explore the palaeobiology and dentition of the giant, undescribed cardabiodontid in the upper Albian Toolebuc Formation. The latter may well have been the largest macrophagous lamniform in the Cretaceous. Its vertebral centra dwarf everything else. 

Btw all but one of the syntypes of Pseudoisurus tomosus have now been located. Unfortunately the missing one is by far the best preserved and the one Glikman himself regarded as the 'type'. If it is found and redescribed properly it is likely that either Cardabiodon (lower probability) or Dwardius (higher probability) will become a junior synonym.

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Macrophyseter
On 3/14/2019 at 1:16 AM, MikaelS said:

Overall there is plenty of work in the pipeline for cardabiodontids as we begin to explore the palaeobiology and dentition of the giant, undescribed cardabiodontid in the upper Albian Toolebuc Formation. The latter may well have been the largest macrophagous lamniform in the Cretaceous. Its vertebral centra dwarf everything else. 

Are you planning to publish a paper on the Albian cardabiodont fossil(s) in the near future? That is really, really exciting for me if it is the case :popcorn:

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MikaelS

Describing the Toolebuc elasmobranchs is a 10-year (well down to 9 now) project (always takes longer than planned) I am doing with the Kronosaurus Korner Museum, Mike Newbrey and amateur collectors. I will not have time to work on this until our new museum opens late in 2020. From there on however we plan to produce a number of publications. The undescribed cardabiodontid is represented by multiple partial skeletons (with or without associated dentitions) as well as a large number of isolated teeth (many of which are in perfect condition). The Eromanga sea was a nursery for this giant lamniform so much of the material is derived from juveniles. One of the things we will be looking at is whether there were two or just one giant cardabiodontid in the Upper Albian. I personally suspect there is only one but we shall see. As I have mentioned elsewhere, North American examples of Albian cardabiodontid vertebrae (from the Kiowa Shale and Duck Creek Fm) have been described under various names (eg Leptostyrax). Williston (1900) btw illustrated a tooth from the Kiowa seemingly indistinguishable from lower laterals of the Eromanga Basin species. It is is likely that this tooth belong to the same species as the big but rather poorly preserved vertebra described by Kenshu.

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