Whittling Down Shark Id Possibilities

[snaggle]

On Elasmo.com, I've seen the Lee Creek shark listings that come from the Pungo and Yorktown formations. On FossilGuy, there is a great page on the shark teeth from Calvert Cliffs. Is it appropriate to extrapolate and use those species listings to help id teeth found in the Yorktown deposit midway between those 2 sites, in tidewater Virginia? I've pulled out my little stash of teeth and there is one that is different from species that seem to dominate what I have. Those sites lead me to consider Lemon or Angel Shark. Is that reasonable?

[siteseer]

On Elasmo.com, I've seen the Lee Creek shark listings that come from the Pungo and Yorktown formations. On FossilGuy, there is a great page on the shark teeth from Calvert Cliffs. Is it appropriate to extrapolate and use those species listings to help id teeth found in the Yorktown deposit midway between those 2 sites, in tidewater Virginia? I've pulled out my little stash of teeth and there is one that is different from species that seem to dominate what I have. Those sites lead me to consider Lemon or Angel Shark. Is that reasonable?

Yes, but keep in mind that a locality even not that far from another given site for the same formation could represent a different time (a million years or more older/younger) and environment (warmer/cooler, shallower/deeper, bay/open ocean, etc.). Your site might yield rather common species that are rare at the Lee Creek mine and vice versa.

I have a 4-inch megalodon from a site on the Rappahannock River which I was told is a Yorktown site. Do you know of this area? Some teeth from there went on the market maybe ten years ago or more but I haven't seen or heard of any since.

[snaggle]

Yes, but keep in mind that a locality even not that far from another given site for the same formation could represent a different time (a million years or more older/younger) and environment (warmer/cooler, shallower/deeper, bay/open ocean, etc.). Your site might yield rather common species that are rare at the Lee Creek mine and vice versa.

I have a 4-inch megalodon from a site on the Rappahannock River which I was told is a Yorktown site. Do you know of this area? Some teeth from there went on the market maybe ten years ago or more but I haven't seen or heard of any since.

Here is another question. Quoting Elasmo.com "Notorynchus cepedianus (PERON, 1807) aka N. primigenius (AGASSIZ, 1843) — Sevengill shark. Traditionally ascribed to primigenius;Purdy, et al (2001) note, these teeth are indistinguishable from the extant species. They attribute them to Pungo units 1-5 and Yorktown 1-2."

What is/are "Yorktown 1-2"? Parts of one formation? Are Pungo 1-5 members of the Yorktown Formation? If this tooth is found in YT 1-2 and I find this same tooth at my collecting site, would it, too, be YT 1-2?

Are some teeth "markers" for a formation or a particular part of a formation?

I'm clueless about what can be found anywhere other than the 1 site that I've collected at. Never been anywhere else. Ideas about visiting Calvert Cliffs and Westmoreland this year are starting to bubble around.

Appreciate your input.

[Northern Sharks]

The Pungo River formation is late miocene and the Yorktown is early pliocene. As for the individual units, I believe I've seen them somewhere, but cannot remember where. You'd be best to check the geology of your area to determine what formations are where. I don't think the Yorktown extends in Maryland and the teeth found at Calvert Cliffs would be more akin to Pungo specimens.

Edited January 31, 2010 by Northern Sharks

[siteseer]

Here is another question. Quoting Elasmo.com "Notorynchus cepedianus (PERON, 1807) aka N. primigenius (AGASSIZ, 1843) — Sevengill shark. Traditionally ascribed to primigenius;Purdy, et al (2001) note, these teeth are indistinguishable from the extant species. They attribute them to Pungo units 1-5 and Yorktown 1-2."

What is/are "Yorktown 1-2"? Parts of one formation? Are Pungo 1-5 members of the Yorktown Formation? If this tooth is found in YT 1-2 and I find this same tooth at my collecting site, would it, too, be YT 1-2?

Are some teeth "markers" for a formation or a particular part of a formation?

I'm clueless about what can be found anywhere other than the 1 site that I've collected at. Never been anywhere else. Ideas about visiting Calvert Cliffs and Westmoreland this year are starting to bubble around.

Appreciate your input.

Snaggle,

"Yorktown 1-2" refer to the uppermost two rock layers of the Yorktown but they do not correspond to the four named members of the formation. Multiple layers constitute a formation. A member, also made up of multiple layers, is a division of a formation often of a different rock composition and may or may not extend across a wide geographic area. A formation may or may not be divided into members and those that do may not have named members.

The Pungo River is a separate formation from the Yorktown. The Pungo ranges from Early to Middle Miocene age; the Yorktown is Early Pliocene.

Some shark species have survived a long time (more than ten million years)so they tend to be unsuitable index fossils. Depending on the species and depending on what else is found with that species, you can sometimes say whether the age is roughly Middle Miocene or Early Pliocene. If you find a Galeocerdo cuvier tooth, you know you are in the Yorktown because that species did not exist during Pungo River time, but then that helps only if those are the only two formations that shark teeth are found where you are collecting. Many invertebrates and identifiable land mammal teeth are more precise time markers.

I have done most of my collecting in one layer and one area as well. I had taken geology classes before and been interested in prehistoric animals since first grade so I had an understanding of how what I was finding fit into earth history. It's just a matter of continuing to take it to the next level of understanding by reading what I can about related topics and seeing what other people find in the same layer or layers of about the same age elsewhere in the world.

[snaggle]

Thank you, Siteseer and Northern Sharks.

I'll post my ID in the ID section.

Edited February 1, 2010 by snaggle

[Paleoc]

Snaggle,

"Yorktown 1-2" refer to the uppermost two rock layers of the Yorktown but they do not correspond to the four named members of the formation. Multiple layers constitute a formation. A member, also made up of multiple layers, is a division of a formation often of a different rock composition and may or may not extend across a wide geographic area. A formation may or may not be divided into members and those that do may not have named members.

The Pungo River is a separate formation from the Yorktown. The Pungo ranges from Early to Middle Miocene age; the Yorktown is Early Pliocene.

Some shark species have survived a long time (more than ten million years)so they tend to be unsuitable index fossils. Depending on the species and depending on what else is found with that species, you can sometimes say whether the age is roughly Middle Miocene or Early Pliocene. If you find a Galeocerdo cuvier tooth, you know you are in the Yorktown because that species did not exist during Pungo River time, but then that helps only if those are the only two formations that shark teeth are found where you are collecting. Many invertebrates and identifiable land mammal teeth are more precise time markers.

Yorktown zones 1 & 2 are the lowest zones of the Yorktown. They directly overlie the Pungo River formation. Zone 1 of the Yorktown is characterized by large amounts of phosphate nodules (probably reworked from the missing Late Miocene) and dates to the Early Pliocene. The Pungo formation is roughly the equivalent of the Calvert formation in Virginia and Maryland (there is no Yorktown formation in Maryland). In Virginia between the Pungo and the Yorktown lies the Choptank, St. Mary's and Eastover formations all of which are missing at Lee Creek.

http://www.elasmo.com/frameMe.html?file=refs/chronostratig.html&menu=bin/menu_refs-alt.html

Index fossils for the various formations and zones are invertebrates, typically shells.

[Paleoc]

Here is another question. Quoting Elasmo.com "Notorynchus cepedianus (PERON, 1807) aka N. primigenius (AGASSIZ, 1843) — Sevengill shark. Traditionally ascribed to primigenius;Purdy, et al (2001) note, these teeth are indistinguishable from the extant species. They attribute them to Pungo units 1-5 and Yorktown 1-2."

What is/are "Yorktown 1-2"? Parts of one formation? Are Pungo 1-5 members of the Yorktown Formation? If this tooth is found in YT 1-2 and I find this same tooth at my collecting site, would it, too, be YT 1-2?

Are some teeth "markers" for a formation or a particular part of a formation?

I'm clueless about what can be found anywhere other than the 1 site that I've collected at. Never been anywhere else. Ideas about visiting Calvert Cliffs and Westmoreland this year are starting to bubble around.

Appreciate your input.

YT 1-2 are depositional zones within the Yorktown formation, in this case the 2 lowest zones.

Pungo 1-5 are the 5 lowest zones within the Pungo formation (roughly equivalent to the Calvert formation in Virginia which has its own zones which don't equate to the ones in the Pungo)

Zones are marked by changes in texture and content of the material to include fossils. For example one zone may be marked by the large rocks, the next by blue clay, the next by yellow sandy clay, another by large amounts of a particular shell.

Teeth are usually very poor indicators of zones as a species can last for tens of millions of years. For example, one can find Physogaleus contortus from the Oligocene (~35 million years ago (MYA) to the late Miocene ~5 MYA)

[snaggle]

YT 1-2 are depositional zones within the Yorktown formation, in this case the 2 lowest zones.

Pungo 1-5 are the 5 lowest zones within the Pungo formation (roughly equivalent to the Calvert formation in Virginia which has its own zones which don't equate to the ones in the Pungo)

Zones are marked by changes in texture and content of the material to include fossils. For example one zone may be marked by the large rocks, the next by blue clay, the next by yellow sandy clay, another by large amounts of a particular shell.

Teeth are usually very poor indicators of zones as a species can last for tens of millions of years. For example, one can find Physogaleus contortus from the Oligocene (~35 million years ago (MYA) to the late Miocene ~5 MYA)

SO..... Yorktown is above Pungo and Eastover is inbetween..... correct?. My site has these 2 formations (Yorktown and Eastover) that ebb and flow along the length of it. Pungo would be below, sight unseen? Would the Eastover be the zone with the blue clay?

Would Lee Creek be different primarily in the lack of Eastover species, ie., species of shark, whale, bivalves, and similar to the Yorktown zone? If I were to venture into a new area, where would the greastest new diversity be...... Lee Creek, Westmoreland, Clavert Cliffs??? Once the mosquitos die back........

Are the Y1-2 (you called them the 2 lowest zones) members like St. Mary's, etc?

Thanks for finding this old post and giving me some good information! I love to learn.

A.