Florida Tooth For Id Please

[jcbshark]

Thank you very much Bobby!: )

[tmaier]

2) Just because Eurhinodelphis hasn't been reported from Florida yet doesn't excuse it as a possibility:

This is good logic. Many times when confronted with a specimen that doesn't fit into the known flora or fauna list of a formation, people shoehorn it in. This causes fossils to end up with a definitive classification when in actuality there isn't enough evidence or it is actually something rare or not on the list.

Edited September 23, 2014 by tmaier

[Harry Pristis]

Hey all, some points -

1) It's an indeterminate odontocete - and that's about as far as anyone is likely to get. It's a bit on the smallish side for a squalodontid, and striated enamel is widely distributed amongst archaic odontocetes. Even if you find an identical tooth still stuck in a rostrum that's attached to a well-preserved braincase (best case scenario for odontocete fossils), you're liable to find upon discovery of another skull in a totally separate family the same tooth morphology. Odontocete teeth - unlike terrestrial mammals - are primarily not disparate between species. For example, I'd challenge someone to identify isolated delphinid teeth pulled out of modern specimens. Unless you have a cheek tooth of an archaic heterodont odontocete (e.g. squalodontid, squalodelphinid, "dalpiazinid" waipatiid, simocetid, xenorophid, agorophiid, among others) isolated teeth of homodont odontocetes are difficult if not impossible to identify. Because this specimen could equally represent a small squalodontid, a large kentriodontid, an iniid, or a platanistid, it can only be identified to "Odontoceti indet."

2) Just because Eurhinodelphis hasn't been reported from Florida yet doesn't excuse it as a possibility: eurhinodelphinids are amongst the most common middle Miocene odontocetes from the Chesapeake Group, and if anything should be expected from middle Miocene deposits in Florida (upon further prospecting in such levels of the Bone Valley Fm. that produced the Bradley Fauna of Morgan, 1994, for example) - after all, the Eurhinodelphis/Xiphiacetus species complex has been reported from both sides of the Atlantic and beyond. In any case, all North American "Eurhinodelphinus" has been reassigned to Xiphiacetus.

I merely suggested that "Eurhinodelphis has not been reported from Florida, AFAIK."

Isolated odontocete teeth are difficult to reliably identify (per Bobby). When attempting to narrow down an ID of such a tooth, I think it's harmless to disregard teeth from species that haven't been reported from Florida.

Middle Miocene marine deposits are uncommon-to-rare in Florida. We certainly don't know what we don't yet know . . . could Xiphiacetus or a squalodont orTaiga tataricus be discovered in South Florida? Can't totally eliminate the possibility, no matter how remote.

When arguing the so-far unknown, we are dealing with probabilities. If a species to date hasn't been reported from Florida, there arises some degree of probability that it will not be reported in the future. I can't say the degree of that probability, but some presumption is inevitable.

The probability of finding a fossil saiga in Florida is vanishingly-low. The probability of finding a Xiphiacetus is just a bit higher. You can argue that the probability is wrong or misleading or that peripheral evidence makes the case; but, it's all conjecture until the fossils are in hand.

[non-remanié]

Middle Miocene marine deposits like the ones that produce enormous quantities of small megalodon-lineage teeth in the Peace River are uncommon in Florida?

[Auspex]

An 'availability heuristic' can cut both ways; overemphasizing some probabilities ('found here before') and preempting others ('never found here before'). It is a time-saving short cut that most often pays off, but can back you into the "absence-of-evidence" corner if you are not cognizant of it.

[sixgill pete]

Jeff, really nice tooth. Not sure how I missed this post until now. This tooth is very similar to one I found a little over 2 years ago in an Oligocene quarry here in eastern NC. It is labeled as Odontoceti indet. I assumed Squalodon, but we all know what assumed means. This goes to show just how true it is that many of these teeth from different species are so similar, mine Oligocene yours middle Miocene. Bobby's response to my initial post of my tooth allowed me to learn (through some research) much about Odontocete's that I did not know.

link to my post .. http://www.thefossilforum.com/index.php?/topic/29546-is-this-a-squalodon-tooth-i-think-it-is/?hl=%2Bbelgrade+%2Bsqualodon

Man, you find some great stuff down there. One of these winters, I need to make a trip.

Edited September 23, 2014 by sixgill pete

[jcbshark]

I would like to thank everyone that helped me try to pin an ID on this guy. I know it can be difficult especially when you're just relying on pictures and not in the hand. I'm sure it not being of a definate age doesn't help matters but I'm glad I can put it in my case and at least have a better answer when someone asks me what it is, tho I may say it's a smilodon milk tooth or some other incredible piece since no one can be 100% sure lol. Thank you all and Don, my door is always open. Let me know when you'll be here. I hear our winters are pretty nice : )

Edited September 23, 2014 by jcbshark

[Harry Pristis]

Middle Miocene marine deposits like the ones that produce enormous quantities of small megalodon-lineage teeth in the Peace River are uncommon in Florida?

Why do you imagine those are Middle Miocene deposits? Not the case.

[non-remanié]

Probably part of the reason is because I know that even highly experienced and knowledgeable Florida collectors tend to put ages on float finds based upon what species they believe fits best even when there is a good mix of ages represented and jumbled together. Maybe that works alright with land mammals.... But mostly I assumed it because all I really ever see is small Meg teeth from Florida, and whether or not it was a nursery ground, there should be larger ones if Megalodon were around. So I assumed big megs were not around yet for most of the time period represented by the deposits, which corresponds better with Middle Miocene aged sediments. So please inform me better. It really is difficult to get good information on this. The Bradley fauna of Morgan that Bobby spoke of comes up as Middle Miocene to me. Perhaps its not exposed or productive in the Peace River. I have never been there or ever collected in Florida at all but much of the info I am getting just says Miocene-Pliocene.

The absolute best way that I have found to predict the fossils found in some deposit is by faunal comparison from nearby similarly aged rocks. I see middle miocene deposits named in Florida (per Bobby) so why do we have to argue about "oh well that hasnt been reported yet"? I can list many taxa that have never been officially reported in NJ and yet I have found them to occur here, and I am not surprised at all because the nearest rocks of similar ages in Md and Va have the same faunal elements. The same is true for the late cretaceous of NJ as compared to further away, just about anywhere in Gulf Coastal Plain and Western Interior Seaway deposits. Maybe Florida is just special and that does not hold true there.... but I doubt it.

[Harry Pristis]

The last inundation of Florida lasted from 4.5 Ma to 2.5 Ma. The vast majority of shark fossils from Florida come from the resulting sediments. I sometimes think of it as the "Mio-Pliocene" (4.5 Ma), but technically, these shark teeth and other marine fossils from the Peace River are predominantly Early Pliocene.

[Plantguy]

The last inundation of Florida lasted from 4.5 Ma to 2.5 Ma. The vast majority of shark fossils from Florida come from the resulting sediments. I sometimes think of it as the "Mio-Pliocene" (4.5 Ma), but technically, these shark teeth and other marine fossils from the Peace River are predominantly Early Pliocene.

Hi Harry, I finally got to looking tonight at the geologic map of the area that we've been collecting from and according to the Geologic Map of Manatee County, Florida by Ken Campbell 1993 the surface rocks are Thpr-Peace River Formation of the Hawthorne group.

I can tell you that there was quite a mix of stuff there and unfortunately mostly surface finds. They've dug a small retention pond at the site and spread the diggings around so I suspect we have a chance at finding older material. I found some of the usual Plio-Pleistocene invertebrate shell material and a number of shark teeth including Meg and ray teeth/tail spine fragments and quite a few small fragments of bone. The couple of bone fragments that I was asking everyone about in the other recent ID thread are from this site (not the horse teeth in that thread). I did also find some turtle and a few fragments of horse teeth there.

Regards, Chris

[Search4]

In some of the sites very close to this one my friends found a few Galeocurdo mayumbenisis , I know that I had never found any of those down here near me and from what I read they are supposed to be a middle Miocene shark.

G. Mayumbenisis, and Galeocerdo contortus, etc. The one with the nickel is yours btw! I read they reigned early Oligocene through late Miocene but died out in the Miocene?

Peace river formation.

Edited September 24, 2014 by Search4

[Al Dente]

The Peace River Formation extends through the Middle Miocene, Upper Miocene and into the Pliocene. The Bone Valley Member of the Peace River Formation (where the phosphate mining occurs) is a highly reworked member that contains some fossils that are older than the deposit itself. MacFadden and Webb (1982) found the age of the fossils within the BVM range from Early Miocene to Early Pliocene.

This stratigraphic section is from the 2012 Southeastern Geological Society Field Trip Guidebook #57:

[Harry Pristis]

The Peace River Formation extends through the Middle Miocene, Upper Miocene and into the Pliocene. The Bone Valley Member of the Peace River Formation (where the phosphate mining occurs) is a highly reworked member that contains some fossils that are older than the deposit itself. MacFadden and Webb (1982) found the age of the fossils within the BVM range from Early Miocene to Early Pliocene.

This stratigraphic section is from the 2012 Southeastern Geological Society Field Trip Guidebook #57:

Florida strat.JPG

I understand that this can be confusing, Al Dente. You must separate the land mammal fossils from the marine fossils in order to understand the chronology. Miocene land mammals are the ones which are reworked into Early Pliocene marine sediments. Land mammal fossils predate the inundation of 4.5 Ma, but are mixed into the post-inundation marine sediments.

South Florida was a high-energy environment with storms, tides, and flooded rivers. The Peace River itself is a high-energy stream environment, in the geological sense.

The same mixing is happening as we speak (with somewhat less energy, I think). For example, Pleistocene mammoth fossils, from a time when sea levels were 300 feel lower, are now being buried in Holocene marine sediments off the coast.

[Al Dente]

Miocene land mammals are the ones which are reworked into Early Pliocene marine sediments.

As are Miocene marine fossils. Search4 pointed out the contortus and mayumbensis teeth that are found. Neither of these lived in the Pliocene.

[Harry Pristis]

As are Miocene marine fossils. Search4 pointed out the contortus and mayumbensis teeth that are found. Neither of these lived in the Pliocene.

I don't think that a few (and they are few) holdover species from their end-Miocene extinction affects the geology or paleontology of South Florida marine deposits. There was no great extinction event at 5 Ma that I am aware of. Perhaps the holdovers, coupled with the admixture of Miocene land vertebrates, contributes to the notion of "Mio-Pliocene" for the 4.5 Ma marine deposits.