Show us your Carpet Sharks fossils !

[fossilsonwheels]

Rhincodon typus

Oligocene

Chandler Bridge Formation 

Summerville South Carolina

 

Pretty happy to have added another Whale Shark tooth to the collection 

[ThePhysicist]

Finally acquired a Maastrichtian Restesia, it hasn't changed much from its Campanian forbears we see in TX!

 

Restesia americana

Hell Creek Fm., Garfield Co., MT, USA

 

4 hours ago, fossilsonwheels said:

Rhincodon typus

Oligocene

Chandler Bridge Formation 

Summerville South Carolina

 

Pretty happy to have added another Whale Shark tooth to the collection 

Oh wow Oligocene is fairly old for R. typus, no?

[digit]

6 hours ago, ThePhysicist said:

Oh wow Oligocene is fairly old for R. typus, no?

Quite old. According to online sources R. typus extends back 28.4 Ma into the Rupelian of the Oligocene. It seems unlikely that a single species would have a span of nearly 30 Ma. The problem with shark fossils has always been that (except for rare specimens) we mostly only have isolate teeth (and occasional vertebral centra). Since Whale Sharks, Basking Sharks, and Megamouth Sharks are filter feeders, they do not actually make use of their teeth for feeding--they are basically vestigial. If they were functional I would expect changes in food availability/preference over deep time should affect the shape and function of a tooth. Whale Sharks may be so well adapted to their environment that they have had little need to evolve for the last 30 Ma but all we know is that their teeth have not changed significantly to be distinguishable from our extant giant. For all we know the Oligocene individual, from which that beautiful tooth above came, might have been pink with purple spots (that'd be a sight!) or could have had distinctive morphological features that would clearly separate it as being separate from our modern species--but we'll never know from a single conservative tooth.

 

Scientists estimate that some invertebrate species may span 5-10 Ma though mammal species tend to only exist for 1-2 Ma. These are, of course, only averages and estimates and in periods of environmental change (or after extinction events) species diversification may happen at a much more accelerated rate.  Well adapted species in a stable environment may last longer but in the end we must remember that nature cares little about 'species' which is a construct humans have created to make sense of a complicated world.

 

For recent (e.g. Plio/Pleistocene) fossils that are indistinguishable from modern extant species I'm comfortable using the current taxon to identify the fossil material. The further back in time a specimen goes the more likely I am to be conservative and hedge with a "cf." (confer) which has the meaning of "refer to or compare with".

 

A bit divergent from the topic of this thread but (hopefully) useful knowledge.

 

 

Cheers.

 

-Ken

[siteseer]

17 hours ago, fossilsonwheels said:

Rhincodon typus

Oligocene

Chandler Bridge Formation 

Summerville South Carolina

 

Pretty happy to have added another Whale Shark tooth to the collection 

 

The first time I saw whale shark teeth from the Chandler Bridge was in the late 90's.  There was a fossil dealer who started buying and trading for smaller teeth/micros and reseling them.  He had a few of these and I bought the last two he had.  He had a few even smaller teeth of other sharks.  I'm not sure I've seen another Rhincodon tooth available from there in years (maybe 1 or 2 about 10 years ago).

 

[fossilsonwheels]

On 6/25/2023 at 7:01 AM, digit said:

Quite old. According to online sources R. typus extends back 28.4 Ma into the Rupelian of the Oligocene. It seems unlikely that a single species would have a span of nearly 30 Ma. The problem with shark fossils has always been that (except for rare specimens) we mostly only have isolate teeth (and occasional vertebral centra). Since Whale Sharks, Basking Sharks, and Megamouth Sharks are filter feeders, they do not actually make use of their teeth for feeding--they are basically vestigial. If they were functional I would expect changes in food availability/preference over deep time should affect the shape and function of a tooth. Whale Sharks may be so well adapted to their environment that they have had little need to evolve for the last 30 Ma but all we know is that their teeth have not changed significantly to be distinguishable from our extant giant. For all we know the Oligocene individual, from which that beautiful tooth above came, might have been pink with purple spots (that'd be a sight!) or could have had distinctive morphological features that would clearly separate it as being separate from our modern species--but we'll never know from a single conservative tooth.

 

Scientists estimate that some invertebrate species may span 5-10 Ma though mammal species tend to only exist for 1-2 Ma. These are, of course, only averages and estimates and in periods of environmental change (or after extinction events) species diversification may happen at a much more accelerated rate.  Well adapted species in a stable environment may last longer but in the end we must remember that nature cares little about 'species' which is a construct humans have created to make sense of a complicated world.

 

For recent (e.g. Plio/Pleistocene) fossils that are indistinguishable from modern extant species I'm comfortable using the current taxon to identify the fossil material. The further back in time a specimen goes the more likely I am to be conservative and hedge with a "cf." (confer) which has the meaning of "refer to or compare with".

 

A bit divergent from the topic of this thread but (hopefully) useful knowledge.

 

 

Cheers.

 

-Ken

Hi Ken 

 

I was pretty surprised to learn that the extant Rhincodon species went back to as far the Oligocene. I originally learned it through Elasmo. This tooth was labeled as cf but those extra two letters are to much extra typing for me lol 

 

Kurt

[fossilsonwheels]

On 6/25/2023 at 1:12 PM, siteseer said:

 

The first time I saw whale shark teeth from the Chandler Bridge was in the late 90's.  There was a fossil dealer who started buying and trading for smaller teeth/micros and reseling them.  He had a few of these and I bought the last two he had.  He had a few even smaller teeth of other sharks.  I'm not sure I've seen another Rhincodon tooth available from there in years (maybe 1 or 2 about 10 years ago).

 

The source of this tooth had a couple for sale. I was happy to grab one. I may grab another lol