Hemipristis puzzle

[sharkdoctor]

Any thoughts appreciated on the following.

I've been working with some material from the Old Church Formation, including previously undescribed sites. The following tooth is from that work. It has most of the characteristics of an early Hemipristis curvatus (Or Hemipristis serra, if you follow Muller). Muller reports two possible teeth that are close to this shape from the Old Church: early Hemipristis serra and Galeorhinus aff galeus. What follows are three photos. 1) The tooth I found and am hoping to identify, 2) a Hemipristis serra from Muller, 1999 and 3) a Galeorhinus aff galeus from Muller, 1999. I lean strongly towards H. serra, but the tooth lacks serrations on the mesial edge. This makes me think that it may be a very early transitional or that there are some positional distinctions that I've not picked up on. The root and distal edge are much more consistent with H. serra.

 

1) The tooth I found and am hoping to identify (scale box=5mm):

 

2) a Hemipristis serra from Muller, 1999

 

3) a Galeorhinus aff galeus from Muller, 1999 (teeth labelled 1a, 2 and 1b)

 

Full citation for photos 2 and 3: Müller, A. (1999). Ichthyofaunen aus dem atlantischen Tertiär der USA. Institut für Geophysik und Geologie.

@Gizmo

[Al Dente]

Galeorhinus all have the enamel bulge overhanging the root like you see in 1b. I have a couple similar teeth like you found and thought they were some type of odd triakid. I showed one to someone else who argued strongly that it was an immature Hemipristis.

[Al Dente]

16 minutes ago, sharkdoctor said:

I lean strongly towards H. serra, but the tooth lacks serrations on the mesial edge. This makes me think that it may be a very early transitional or that there are some positional distinctions that I've not picked up on.

Have you seen this paper? It includes Oligocene and Eocene Hemipristis.

 

[Al Dente]

I think Paragaleus might be a better fit for your tooth. Depends on what the other side looks like. Here's a modern Paragaleus.

 

 

[sharkdoctor]

Thanks for the paper and your thoughts on this, @Al Dente!

 

The labial surface of the tooth is below, in case it is useful. I am also going to add a few other photos of Hemi's from this formation.

 

Labial surface of tooth I found and am hoping to identify (scale box=5mm):

 

Below is a Hemipristis curvatus from the Old Church Formation. The mesial edge doesn't have serrations (but there are some possible crenellations?):

 

Hemipristis curvatus, lingual side, Old Church Formation (scale box=5mm):

:

 

Hemipristis curvatus, labial side, Old Church Formation (scale box=5mm):

 

 

 

 

[Searcher78]

Nice tooth.  The root along with no bulge along the root tells me Hemi.

[sharkdoctor]

@Searcher78

Interesting point! I am hoping to work a new site this spring that has less leaching in hopes of finding some more of these that have better definition of the root and nutrient groove.

[sharkdoctor]

As an update, the tooth labelled H. curvatus, above, is referred to as a juvenile H. serra in Cicimurri & Knight (2009).

 

Reference: Cicimurri, D. J., & Knight, J. L. (2009). Late Oligocene sharks and rays from the Chandler Bridge Formation, Dorchester County, South Carolina, USA. Acta Palaeontologica Polonica, 54(4), 627-648.

[Searcher78]

7 hours ago, sharkdoctor said:

As an update, the tooth labelled H. curvatus, above, is referred to as a juvenile H. serra in Cicimurri & Knight (2009).

 

Reference: Cicimurri, D. J., & Knight, J. L. (2009). Late Oligocene sharks and rays from the Chandler Bridge Formation, Dorchester County, South Carolina, USA. Acta Palaeontologica Polonica, 54(4), 627-648.

Interesting, I was just thinking what if it is a juvenile and serrations become more pronounced as an adult.