Extant Anoxypristis cuspidata (Knifetooth or Narrow Sawfish) rostrum

[MarcoSr]

A post by YNOT @ynot on STH teeth peaked my interest in extant sawfish rostral teeth.  The two extant sawfish genera are Pristis and Anoxypristis.   There is only a single extant Anoxypristis species, Anoxypristis cuspidata (Knifetooth or Narrow Sawfish).   There are 4 extant  species of Pristis, Pristis clavata (Dwarf Sawfish), Pristis pectinata (Smalltooth Sawfish), Pristis pristis (Largetooth Sawfish), and Pristis zijsron (Green Sawfish) Last 2016.  I borrowed an Anoxypristis cuspidata rostrum from a friend so I could take pictures of it.

 

The rostrum is 18” long and is shown below in dorsal and ventral views:

 

  

 

The basal view of the rostrum (35 mm by 13 mm) shows a thin layer of grey skin on the dorsal side and a thin layer of yellow skin on the ventral side above the white cartilage of the rostrum.

 

 

 

 

Below are pictures of 8 different rostral teeth (6 mm to 14 mm vertical height)

 

6 teeth dorsal views:

 

 

2 teeth ventral views:

 

 

Continued in next reply

Marco Sr.

 

[MarcoSr]

Fossil Anoxypristis mucrodens rostral tooth (22 mm) from the Eocene of Virginia for comparison to the extant Anoxypristis teeth

 

 

Pictures of the placoid scales that cover the skin on the rostrum

 

Dorsal view:

 

 

Ventral view:

 

 

 

Marco Sr.

Edited January 12, 2019 by MarcoSr
correct placoid scale discussion

[Darktooth]

Very interesting,  Thank-you for sharing this.

[Tidgy's Dad]

Fascinating! 

As I have said i love these "now and then" posts. 

[ynot]

Nice dissertation Marco!

I think the pattern is placoid scales. (mainly because I do not see anything else that could be placoid scales and I know that they should be there). Also, there are a few places where they have fallen out.

[MarcoSr]

48 minutes ago, ynot said:

Nice dissertation Marco!

I think the pattern is placoid scales. (mainly because I do not see anything else that could be placoid scales and I know that they should be there). Also, there are a few places where they have fallen out.

 

Tony

 

What is confusing me is that in most rays (sawfish are rays) placoid scales are generally scattered sparsely and unevenly across the upper surface of the head, body and pectoral fins,  Welton 1993.  These structures completely cover both the dorsal and ventral sides of the rostrum.  Maybe a sawfish rostrum is an exception to the general rule.  Also the structures really don't look like the normal placoid scales that I see.  I've also read that juvenile Anoxypristis rostrums have smooth skin and adult rostrums have scattered dermal denticles on the dorsal side. I've looked pretty closely at the rostrum and didn't see anything different looking that might be a dermal denticle.

 

Marco Sr.

[Shellseeker]

Thanks very much for sharing.  I have saved a number of your photos and bookmarked this thread. I had not found a rostral tooth for what seemed like years and then 2 weeks ago, found 4 or 5,

Seems to be a relative. Mine is very small...

[MarcoSr]

1 hour ago, Tidgy's Dad said:

Fascinating! 

As I have said i love these "now and then" posts. 

 

The Anoxypristis rostral teeth that I have from the Eocene of Virginia really don't look different from the extant ones.

 

Marco Sr.

[MarcoSr]

1 hour ago, Darktooth said:

Very interesting,  Thank-you for sharing this.

 

It is interesting for me also because I'm not sure what the structures are that I'm seeing in the close-up pictures.

 

Marco Sr.

[Tidgy's Dad]

2 minutes ago, MarcoSr said:

 

The Anoxypristis rostral teeth that I have from the Eocene of Virginia really don't look different from the extant ones.

 

Marco Sr.

Yes, and that's amazing to think it's barely changed for 50 odd million years. 

[MarcoSr]

6 minutes ago, Shellseeker said:

Thanks very much for sharing.  I have saved a number of your photos and bookmarked this thread. I had not found a rostral tooth for what seemed like years and then 2 weeks ago, found 4 or 5,

Seems to be a relative. Mine is very small...

 

Really nice condition on your tooth when you can clearly see the pattern on the tooth.   Pristis teeth have a very visible grove down one side.  Anoxypristis don't have the grove and are more symmetrical.

 

Marco Sr.

[doushantuo]

Entertaining post!!!!I like it.

[MarcoSr]

28 minutes ago, Tidgy's Dad said:

Yes, and that's amazing to think it's barely changed for 50 odd million years. 

 

Unfortunately now Anoxypristis is an endangered species.  Over fishing has not only drastically reduced their numbers it has also drastically reduced the size of the largest members of the species.  So you don't see the max size specimens and the average size of the species has gotten smaller and smaller.

 

It is even worse for Pristis species.  Three of the four species are critically endangered and the fourth is endangered.

 

Marco Sr.

[Tidgy's Dad]

3 minutes ago, MarcoSr said:

 

Unfortunately now Anoxypristis is an endangered species.  Over fishing has not only drastically reduced their numbers it has also drastically reduced the size of the largest members of the species.  So you don't see the max size specimens and the average size of the species has gotten smaller and smaller.

 

It is even worse for Pristis species.  Three of the four species are critically endangered and the fourth is endangered.

 

Marco Sr.

Tragic. 

[MarcoSr]

17 minutes ago, doushantuo said:

Entertaining post!!!!I like it.

 

Thank you.  I really believe you need to understand the extant species in order to better understand the fossil ones.

 

Marco Sr.

[MarcoSr]

As an update to this post, Dr. Bruce Welton pointed me to a paper, Casier, E, 1949.  Contributions a L'etude des poisons fossils de la Belgique.  VIII. Les Pristides eocenes, that described the structures that I was seeing on the rostrum surface.  See the below figure from that paper:

 

 

For those that can't read French the figure describes an external calcified layer of balusters that fully covers the external surface of an Eocene Pristis rostrum from Belgium.  You can see this calcified layer  in the pictures below for the rostrum in this post.  So the structures weren't placoid scales or the prismatic structure of the rostrum cartilage below.

 

  Close-up basal view of the rostrum:

 

 

 

Close-up dorsal views of the rostrum:

 

 

 

 

Marco Sr.

[doushantuo]

Just tell me what you need translated.I have the paper,all 146 Mb of it

edit: Totally misread your post

[MarcoSr]

1 minute ago, doushantuo said:

Just tell me what you need translated.I have the paper,all 146 Mb of it

 

Thank you, but I have the paper now and I actually can read French very well.  Unfortunately I can't write or speak French well anymore because of lack of doing so in years.

 

Marco Sr.

[doushantuo]

 

Belgian French can be different from French French...

 

 

[MarcoSr]

10 minutes ago, doushantuo said:

 

 

Belgian French can be different from French French...

 

 

 

 

I studied French French in school but actually also spoke Canadian French which can be different from both.

 

Marco Sr.