Paraorthacodus Andersoni

[cowsharks]

While researching Paraorthacodus I came across some references to Paraorthacodus andersoni being found in Blaine County, Montana. Curious to know if anyone has any specimens from there and if so can you show some pics.

The only pic I found of a P. andersoni was on this website: P. andersoni link

I can't read Dutch?, so I'm not certain if the locality of that specimen is listed there somewhere. That particular page is part of this: Main page

Anyhow, just curious to know what P. andersoni specimens from MT look like in comparison to P. clarkii.

Daryl S.

[fossilselachian]

Cowsharks:

Yes, I have examples of P.andersoni from Blaine County, MT. I'm unsure if any name changes have occurred in the years I've had these teeth but they were P. andersoni at the time of acquisition Without looking for them I recall there may be about a half-dozen complete (or nearly so) and others not so. I'll locate them this weekend and post a pic or two.

FS

[cowsharks]

Thanks FS. Do you know anything more about where they are found, formation, rarity, etc.? I thought P. clarkii was the only US species, and only found in MD, until I saw that reference to P. andersoni in MT. Just curious to know how they compare to P. clarkii.

thanks,

Daryl S.

[siteseer]

Daryl,

These are interesting questions. Case described Paraorthacodus andersoni and P. striatus in his 1978 article on a fauna from Blaine County, Montana (site called "Timber Ridge"). Unfortunately, he did not compare it to other known species of the time. He did state that the teeth average 2cm in root width, 1 1/2 cm in height (central cusp apex to root basal margin). I have one P. andersoni anterior-lateral tooth half that size so mine is apparently atypical. From what I've seen P. clarki seem to average around 1cm wide so average size seems to be a distinguishing character.

Mikael Siverson published an article on Paraorthacodus teeth from the Kristianstad Basin, southern Sweden in 1992. He reported P. andersoni and P. conicus from those sites. He also reviewed the known species of the genus. In short he stated:

P. nerviensis is a junior synonym of P. conicus. This is noteworthy in that most-all of the Late Cretaceous Paraorthacodus teeth I've seen from Kazakhstan sites have been identified as P. nerviensis.

P. striatus is not a valid species, merely the posterior teeth of P. andersoni.

P. clarkii, described by Eastman (1901) is based on a sample very poorly illustrated.

Cappetta (1987 - his Chondrichthyes II) suggested that P. eocaenus (a Paleocene species known from Europe) is a junior synonym of P. clarkii. While it is true that clarkii was named a year before Leriche's species, eocaenus, it is possible that clarkii may not be considered valid depending on later interpretation of the quality of the holotype's illustration. I don't have a copy of either illustration at this time so I don't have an opinion on that. I can certainly try to find those.

In his "Fossil Sharks of the Chesapeake Bay Region" Bretton Kent describes P. clarkii teeth from the Aquia Formation but he doesn't compare them to other species from other regions.

I received a Paraorthacodus andersoni tooth from Montana maybe twenty years ago as part of a sample traded to me by a local collector. He told me it was very rare. This species is not known from a layer about the same age in Wyoming (Teapot Sandstone Member of the Mesaverde Formation, Worland area). I received a couple of P. andersoni lateral-posterior teeth a few years ago. Judging from what I've seen of andersoni and clarki, I would say andersoni is a rarer species in its deposit than clarkii is at its sites, keeping in mind that clarkii is hardly common.

I have seen Paraorthacodus from the Early Cretaceous (Albian) of Staryi Oskol, Russia (apparently rare there), the Late Cretaceous (Campanian) Trivieres Chalk of Obourg, Belgium (probably P. conicus - also rare) and P. eocaenus of the Late Paleocene Woolwich Bottom Beds of Beltinge (aka Herne Bay), England (also rare in the deposit). The genus appears to be common in the Santonian of Tykbutak, Kazakhstan (I've seen at least two spelling for Tykbutak).

Suggested references:

Cappetta, H. 1992.

New observations on the palaeospinacid dentition (Neoselachii, Palaeospinacidae). Neues Jahrbuch Geol. Palaont. Monatshefte 1992: 565-570.

Case, G.R. (1978)

A new selachian fauna from the Judith River Formation (Campanian) of Montana. Palaeontographica (A), 160:176-205.

Eastman, C.R. 1901.

Pisces, p. 98-115. In W.B. Clark and G.C. Martin (eds.). Eocene Deposits of Maryland. Maryland Geological Survey, Stratigraphic Memoir, Baltimore.

Leriche, M. 1902.

Les Poissons Tertiaires de la Belgique. 1. Les poissons paleocenes. Extrait des Memoires du Musee Royal d'Histoire Naturelle de Belgique, 5:1-48.

*Leriche's articles are well-illustrated so this is worth looking for. This is one that I am lacking.

Siverson, M. 1992.

Late Cretaceous Paraorthacodus (Palaeospinacidae, Neoselachii) from Sweden. Journal of Paleontology 66 (6):994-1001.

There are other articles you might check within the reference lists of the above publications.

Jess

Thanks FS. Do you know anything more about where they are found, formation, rarity, etc.? I thought P. clarkii was the only US species, and only found in MD, until I saw that reference to P. andersoni in MT. Just curious to know how they compare to P. clarkii.

thanks,

Daryl S.

[fossilselachian]

Cowsharks:

Yes, I have examples of P.andersoni from Blaine County, MT. I'm unsure if any name changes have occurred in the years I've had these teeth but they were P. andersoni at the time of acquisition Without looking for them I recall there may be about a half-dozen complete (or nearly so) and others not so. I'll locate them this weekend and post a pic or two.

FS

Attached are pics of the P. andersoni referenced above. They are not in quite as good condition as I remembered

but then, neither am I.

PS to Siteseer: Did I send you one of these some time in the distant past? If not, let me know.

Edited April 2, 2011 by fossilselachian

[cowsharks]

Daryl,

These are interesting questions. Case described Paraorthacodus andersoni and P. striatus in his 1978 article on a fauna from Blaine County, Montana (site called "Timber Ridge"). Unfortunately, he did not compare it to other known species of the time. He did state that the teeth average 2cm in root width, 1 1/2 cm in height (central cusp apex to root basal margin). I have one P. andersoni anterior-lateral tooth half that size so mine is apparently atypical. From what I've seen P. clarki seem to average around 1cm wide so average size seems to be a distinguishing character.

Mikael Siverson published an article on Paraorthacodus teeth from the Kristianstad Basin, southern Sweden in 1992. He reported P. andersoni and P. conicus from those sites. He also reviewed the known species of the genus. In short he stated:

P. nerviensis is a junior synonym of P. conicus. This is noteworthy in that most-all of the Late Cretaceous Paraorthacodus teeth I've seen from Kazakhstan sites have been identified as P. nerviensis.

P. striatus is not a valid species, merely the posterior teeth of P. andersoni.

P. clarkii, described by Eastman (1901) is based on a sample very poorly illustrated.

Cappetta (1987 - his Chondrichthyes II) suggested that P. eocaenus (a Paleocene species known from Europe) is a junior synonym of P. clarkii. While it is true that clarkii was named a year before Leriche's species, eocaenus, it is possible that clarkii may not be considered valid depending on later interpretation of the quality of the holotype's illustration. I don't have a copy of either illustration at this time so I don't have an opinion on that. I can certainly try to find those.

In his "Fossil Sharks of the Chesapeake Bay Region" Bretton Kent describes P. clarkii teeth from the Aquia Formation but he doesn't compare them to other species from other regions.

I received a Paraorthacodus andersoni tooth from Montana maybe twenty years ago as part of a sample traded to me by a local collector. He told me it was very rare. This species is not known from a layer about the same age in Wyoming (Teapot Sandstone Member of the Mesaverde Formation, Worland area). I received a couple of P. andersoni lateral-posterior teeth a few years ago. Judging from what I've seen of andersoni and clarki, I would say andersoni is a rarer species in its deposit than clarkii is at its sites, keeping in mind that clarkii is hardly common.

I have seen Paraorthacodus from the Early Cretaceous (Albian) of Staryi Oskol, Russia (apparently rare there), the Late Cretaceous (Campanian) Trivieres Chalk of Obourg, Belgium (probably P. conicus - also rare) and P. eocaenus of the Late Paleocene Woolwich Bottom Beds of Beltinge (aka Herne Bay), England (also rare in the deposit). The genus appears to be common in the Santonian of Tykbutak, Kazakhstan (I've seen at least two spelling for Tykbutak).

Suggested references:

Cappetta, H. 1992.

New observations on the palaeospinacid dentition (Neoselachii, Palaeospinacidae). Neues Jahrbuch Geol. Palaont. Monatshefte 1992: 565-570.

Case, G.R. (1978)

A new selachian fauna from the Judith River Formation (Campanian) of Montana. Palaeontographica (A), 160:176-205.

Eastman, C.R. 1901.

Pisces, p. 98-115. In W.B. Clark and G.C. Martin (eds.). Eocene Deposits of Maryland. Maryland Geological Survey, Stratigraphic Memoir, Baltimore.

Leriche, M. 1902.

Les Poissons Tertiaires de la Belgique. 1. Les poissons paleocenes. Extrait des Memoires du Musee Royal d'Histoire Naturelle de Belgique, 5:1-48.

*Leriche's articles are well-illustrated so this is worth looking for. This is one that I am lacking.

Siverson, M. 1992.

Late Cretaceous Paraorthacodus (Palaeospinacidae, Neoselachii) from Sweden. Journal of Paleontology 66 (6):994-1001.

There are other articles you might check within the reference lists of the above publications.

Jess

Thanks a bunch siteseer! Thanks for taking the time to type up all that info and references. The info that you and FS provided is great stuff! I'm going to copy the text and save it off in a separate text file for later reference.

Daryl S.

[cowsharks]

Attached are pics of the P. andersoni referenced above. They are not in quite as good condition as I remembered

but then, neither am I.

PS to Siteseer: Did I send you one of these some time in the distant past? If not, let me know.

FS, thanks so much for posting the pics of your P. andersoni's. The teeth in the first pic look very similar to the P. clarkii that I have. Without studying them side by side they superficillay look very similar. The two teeth in the third pic though, especially the one on the right (a posterior perhaps?), looks different though. The cusps look very short, and not too graduated, and they look to be spaced closer together. It reminds me more of the P. nerviensis specimens I've seen before. I'll have to check my P. clarkii specimens to see if I have a posterior type of specimen.

Thanks again for the help and info.

Daryl S.

[siteseer]

I was looking at that second tooth in the third photo as well. I think it's a Synechodus tooth (a posterior have a lower cusp and cusplets relative to the root than that tooth). Synechodus is the genus to which andersoni and other species were originally assigned before Paraorthacodus was proposed.

FS, thanks so much for posting the pics of your P. andersoni's. The teeth in the first pic look very similar to the P. clarkii that I have. Without studying them side by side they superficillay look very similar. The two teeth in the third pic though, especially the one on the right (a posterior perhaps?), looks different though. The cusps look very short, and not too graduated, and they look to be spaced closer together. It reminds me more of the P. nerviensis specimens I've seen before. I'll have to check my P. clarkii specimens to see if I have a posterior type of specimen.

Thanks again for the help and info.

Daryl S.

[siteseer]

Fossilselachian,

I was trying to think of who else uses that weird red background (avatar). Is your old codename, Ohio Player?

I would certainly welcome any one of those specimens. I think I received one from KO about twenty years ago but don't recall the source of a group of Judith River teeth I received maybe 10-12 years ago (small teeth in little capsules).

Jess

Attached are pics of the P. andersoni referenced above. They are not in quite as good condition as I remembered

but then, neither am I.

PS to Siteseer: Did I send you one of these some time in the distant past? If not, let me know.

[ahuijsmans]

ahum, gentlemen, as I am dutch I can confirm this is not dutch it's danish

Hence the .dk (denmark) at the end of the URL. .NL is for Dutch websites.

Very nice teeth, hope to find one some day in the Maastrichtiaan of Limburg, where the Maastrichtiaan got it's name from..