Lumpy Fossils -- What Are These?

[Harry Pristis]

These bones (and they are bones), have been knocking around my storeroom for a good while. I don't know what they are for certain -- does anyone here know?

The views are front and back, or maybe distal and proximal -- I'm not sure. They are Late Miocene to Pleistocene in age. They may be marine or terrestrial.

The original images of the "lumpy fossils" were lost in one of the forum transitions. There were no other images on-line of these ear bones at the time. I am adding these images, the original plus some new ones, to restore the integrity of the thread for future searches here and maybe on Google:

EDIT: Thanks for doing this, Harry; I merged your new post with the original. 04/08/16 Auspex

[makoken]

These bones (and they are bones), have been knocking around my storeroom for a good while. I don't know what they are for certain -- does anyone here know?

The views are front and back, or maybe distal and proximal -- I'm not sure. They are Late Miocene to Pleistocene in age. They may be marine or terrestrial.

Could they be river worn preiodic bones?

[Harry Pristis]

Could they be river worn preiodic bones?

Yes, they could be periotic bones. They are not much abraded, though.

[Guest bmorefossil]

they are from puffer fish

Sphoeroides hyperostosus

extinct puffer — suboperculum

[Harry Pristis]

they are from puffer fish

Sphoeroides hyperostosus

extinct puffer — suboperculum

I don't think this is a fish bone. It (they, I have at least three) is massive and much larger than the Sphoeroides hyperostosus suboperculum (about one inch at its widest) illustrated on Elasmo.com. Furthermore, my lumpy bones are far more complicated/detailed than the puffer fish suboperculum.

To give you an idea of scale, compare the lumpy bone to the periotic of a small, Miocene sperm whale (Cf. Kogiopsis sp.).

[Bill]

Reminds me of This

[Edo]

Reminds me of This

I think Bill is right (this is one from Mill).

[Pristiformes]

I agree with others that they look to be periotic bones from a marine mammal, although I'm at a loss as to which species it came from. Here is a photo showing a pair of Atlantic bottlenose dolphin ear bones (left side of photo), and a single ear bone from a Florida manatee. I can't say Harry's fossils look too much like either of these, but they seem to be in the ballpark.

[Boesse]

Aside from looking like a piece of bone generally shaped like a piece of popcorn, this element doesn't really resemble a cetacean periotic/petrosal much at all.

However, I think someone should make some comparisons with the sirenian petrosals. Harry, can you see any foramina present on the bone? Mammalian petrosals will always have a visible fenestra vestibuli, foramen rotundum, an obvious cochlea/promontorium, facial nerve foramen, internal acoustic meatus, etc. etc. (take home message: will be riddled with holes).

Bobby

[Boesse]

And by the way, the size of this element is much larger even than that of Physeter, the extant (and largest known) odontocete. So, this is in the size range of mysticetes; this element doesn't really look like any mysticete petrosal I've ever seen (and I'm staring at several as I write). And, come to think of it, I'm not sure Trichechid petrosals are this large either.

So, I'm not really sure. I can't vouch for some kind of teleost exostosed element, though; but I am fairly certain that it isn't a petrosal from some kind of marine mammal.

Bobby

[Guest bmorefossil]

Aside from looking like a piece of bone generally shaped like a piece of popcorn, this element doesn't really resemble a cetacean periotic/petrosal much at all.

Bobby

yep it does not look like a periotic/ petrosal to me thats why i went with something like this.

[Pristiformes]

And by the way, the size of this element is much larger even than that of Physeter, the extant (and largest known) odontocete. So, this is in the size range of mysticetes; this element doesn't really look like any mysticete petrosal I've ever seen (and I'm staring at several as I write). And, come to think of it, I'm not sure Trichechid petrosals are this large either.

You might be on to something here. Harry's fossils each measure roughly 73 mm in longest length, based on the penny in the photo. I measured my Florida manatee earbone complex, and it's longest length measured approximately 71 mm. It came from a stranded mature specimen salvaged and necropsied by FWC biologists during the 1996 red tide event (back when I worked there). So 73 mm seems possible for a large sirenian but it would be rather large at least for a trichechid, although a dugongid may have larger earbones.

[Boesse]

You might be on to something here. Harry's fossils each measure roughly 73 mm in longest length, based on the penny in the photo. I measured my Florida manatee earbone complex, and it's longest length measured approximately 71 mm. It came from a stranded mature specimen salvaged and necropsied by FWC biologists during the 1996 red tide event (back when I worked there). So 73 mm seems possible for a large sirenian but it would be rather large at least for a trichechid, although a dugongid may have larger earbones.

Could you perhaps post some more photos of the Trichechus petrotympanic you have, from multiple angles? I don't have any wonderful photos/publications to compare with, so it would be of immense help in trying to ID Harry's mystery 'lumps'.

Bobby

[Pristiformes]

Could you perhaps post some more photos of the Trichechus petrotympanic you have, from multiple angles? I don't have any wonderful photos/publications to compare with, so it would be of immense help in trying to ID Harry's mystery 'lumps'.

Bobby

I just zipped these off really quick, I hope they came out okay. Sentiel "Butch" Rommel had drafted some nice diagrams of the Florida manatee skeleton back in 1998 while at the FWC Marine Mammal Pathobiology Lab in St. Petersburg. I don't know if he ever got around to publishing them or not.

[Boesse]

That might be a good match. If these are as old as middle Miocene, then these could be Metaxytherium (although I confess, I don't know if it made it into the late Miocene). But definitely a potential dugongid.

Bobby

[Pristiformes]

That might be a good match. If these are as old as middle Miocene, then these could be Metaxytherium (although I confess, I don't know if it made it into the late Miocene). But definitely a potential dugongid.

Bobby

Looking at Hulbert (2001), it says that Metaxytherium crataegense occurred in the early to mid-Miocene while M. floridanum existed in the mid to late-Miocene in Florida.

[Harry Pristis]

Looking at Hulbert (2001), it says that Metaxytherium crataegense occurred in the early to mid-Miocene while M. floridanum existed in the mid to late-Miocene in Florida.

And that's what I think these are -- Metaxytherium floridanum ear bones. They do have foramina. I will post some more images as soon as I can.

I searched the www earlier today, but could not find an image of a dugong petrosal or periotic or petrotympanic (a great word!).

Great input, fella's!

[Boesse]

And that's what I think these are -- Metaxytherium floridanum ear bones. They do have foramina. I will post some more images as soon as I can.

I searched the www earlier today, but could not find an image of a dugong petrosal or periotic or petrotympanic (a great word!).

Great input, fella's!

Hey Harry, no problem. Petrotympanic or tympanoperiotic (generally European scientists use the latter) basically just refers to when the periotic and tympanic are fused, or in the case of cetaceans, still fused; or also, if you would like to refer to the entire complex, it shortens up things in a manuscript by a little bit.

Bobby

[Harry Pristis]

Hey Harry, no problem. Petrotympanic or tympanoperiotic (generally European scientists use the latter) basically just refers to when the periotic and tympanic are fused, or in the case of cetaceans, still fused; or also, if you would like to refer to the entire complex, it shortens up things in a manuscript by a little bit.

Bobby

Good to know. I don't have a lot of experience with marine mammals.

As I understand it, some mammals (marine mammals only?) have tympanic bulla and periotic fused, and some don't. Some whales, mysticetes and odontocetes for example, have separate or non-fused bullae and periotic bones. Is that correct?

I don't know the morphology of dugongs, but does it appear that these putative Metaxytherium petrotympanics are fused elements?

Are the manatee petrotympanics considered fused or non-fused? I have a handful of the (probably) tympanic bullae from manatees, but have never identified a periotic. Here's a comparison shot of dugong(?) and manatee ear bones.

[Guest bmorefossil]

not sure about manatee but yes some are fused

[Boesse]

Good to know. I don't have a lot of experience with marine mammals.

As I understand it, some mammals (marine mammals only?) have tympanic bulla and periotic fused, and some don't. Some whales, mysticetes and odontocetes for example, have separate or non-fused bullae and periotic bones. Is that correct?

I don't know the morphology of dugongs, but does it appear that these putative Metaxytherium petrotympanics are fused elements?

Are the manatee petrotympanics considered fused or non-fused? I have a handful of the (probably) tympanic bullae from manatees, but have never identified a periotic. Here's a comparison shot of dugong(?) and manatee ear bones.

Good questions. Let me see if I can answer these...

In cetaceans, the petrotympanic complex has lost all bony articulations with the skull, apparently related to the development of the peribullary sinus, which helps to acoustically isolate the earbones from the skull, in order for directional hearing to be possible (if the articulation were still there, then they would hear via bone conducted hearing, like all other mammals, which is directional in air, but not while submerged). I believe that the periotic and tympanic are still fused together, albeit isolated as a whole from the skull. The periotic-tympanic articulations/fusion is less extreme than in terrestrial mammals. In odontocetes, there are two major places where the tympanic and periotic are articulated - the posterior process, and near the sigmoid process (basically, near the malleus/incus/stapes complex). In mysticetes, the posterior process articulation is much reduced, and the tympanics break off much more easily. In odontocetes, the articulation is not extremely strong either, so these elements frequently separate from eachother.

The loose attachment of the petrotympanics to the skull is why so many skulls lack them; mysticete skulls often lack tympanics, and odontocete skulls often lack both - the periotic in mysticetes often has several articulations, and is lodged within a cavity called the cranial hiatus. The periotic is also known as the petrosal - which is what its called when it is still fused to the skull, as in terrestrial mammals. There is some debate whether or not to call it a periotic or petrosal in mysticetes, as primitive whales all have periotics, but there is a slight articulation with the skull in mysticetes. I've been instructed to use both terms by different paleontologists; when I start writing, I'll probably follow my coauthor's terminology.

Bobby

[mommabetts]

Thanks for that very good explanation.

[Harry Pristis]

Thank you, Bobby, for the description of the petrotympanic in whales. Since we're dealing only with isolated ear bones, I've tried to disregard mention of articulation/fusion with the whale skull -- to avoid confusion over fusion, so to speak. Let's see if I have it correct.

"In cetaceans, the petrotympanic complex has lost all bony articulations with the skull, ...which helps to acoustically isolate the earbones from the skull, in order for directional hearing to be possible.... I believe that the periotic and tympanic are still fused together, albeit isolated as a whole from the skull.

The periotic-tympanic articulations/fusion is less extreme than in terrestrial mammals. In odontocetes, there are two major places where the tympanic and periotic are articulated - the posterior process, and near the sigmoid process (basically, near the malleus/incus/stapes complex). In mysticetes, the posterior process articulation is much reduced, and the tympanics break off much more easily. In odontocetes, the articulation is not extremely strong either, so these elements frequently separate from eachother.

... The periotic is also known as the petrosal - which is what its called when it is still fused to the skull, as in terrestrial mammals. There is some debate whether or not to call it a periotic or petrosal in mysticetes, as primitive whales all have periotics, but there is a slight articulation with the skull in mysticetes. I've been instructed to use both terms by different paleontologists...."

That is instructive; but, what about the "lumpy bones"? The tympanic bulla and the periotic (if that's what they are) seem to be fused/articulated over a larger surface than the manatee bullae I have before me. Do you have any info on dugong petrotympanics that can help us?

[Boesse]

Well, I figured the info about cetaceans would at least be helpful, considering that you probably have quite a few of them.

As far as sirenians, I don't have any publications with photographs or figures of their earbones, and I can't recall any papers that at the very least describe them in much detail (harder to digest than photos, to be sure).

In general, I have read that the auditory system of sirenians is similar, in that the petrotympanic is no longer articulated (much) with the skull, but its been a while since I've read the Berta et al. marine mammals textbook.

As far as the fusion of your lumpy elements/probable dugongid earbones - I can't tell from comparing with those photos (either because they are at different angles, or if they are, the recent specimens still have so much of the tympanic attached that it is obscuring the view) what exactly is going on. However, from what I've seen, it *looks* like what you have is the lateral portion of the petrosal, and the promontorium is broken away. The promontorium/cochlea is the round, spherical feature on say odontocete periotics; this structure houses the semicircular canals. This seems to be missing on your specimens. This commonly breaks off in odontocetes, leaving an even weirder looking bone than before. Then again, I haven't looked at the photos in several hours; I'll get back to you on this shortly.

Hope this helps - my expertise with sirenian material is very limited, especially compared to cetaceans.

However, give me a couple days, I'll take another (longer) glance at Domning (1978), and see what he says about Dusisiren jordani, a close relative of Metaxytherium.

Bobby

[Guest bmorefossil]

\

The periotic-tympanic articulations/fusion is less extreme than in terrestrial mammals. In odontocetes, there are two major places where the tympanic and periotic are articulated - the posterior process, and near the sigmoid process (basically, near the malleus/incus/stapes complex). In mysticetes, the posterior process articulation is much reduced, and the tympanics break off much more easily. In odontocetes, the articulation is not extremely strong either, so these elements frequently separate from eachother.

yes there is a very thin articulation between the two, in the partial skull I found, they were already broke but still in place.