Why are jaw fossils common?

[aplomado]

Someone I read a joking statement that paleontology is primarily "the study of fossil teeth and jaws."

Teeth and jaw fossils do appear to predominate....

 

I understand why tooth fossils are common- teeth are very hard, and many creatures replace teeth repeatedly.

But why are jaw fossils common?

[ynot]

I think that jaws are not really any more common than other types of bone fossils, they just get more publicity than other bones do.

[jcbshark]

I would say they're relatively rare down my way although they are one of my favorite things to find. I maybe have 10 pieces over the years I've found 

[Shellseeker]

2 hours ago, aplomado said:

Someone I read a joking statement that paleontology is primarily "the study of fossil teeth and jaws."

Teeth and jaw fossils do appear to predominate....

 

I understand why tooth fossils are common- teeth are very hard, and many creatures replace teeth repeatedly.

But why are jaw fossils common?

Are they common in your hunting grounds?  Scarce as hens teeth in mine..

[Harry Pristis]

I don't think there is a single reason that a jaw might survive when post-cranials might not.  First, jaws are dense bone, re-inforced by interior stringers of bone.  Lower jaws survive better than upper, maxillary bone because there is less dense cortex in the upper.  Those upper teeth instead are supported by a broad base of trabecular bone. 

 

Second, there is little for a carnivore to chew on when it comes to the skull.  If the choice is chewing on a face or a flank, the latter is going to get the destructive attention. 

 

Third, there is likely to be a collecting bias involved:  a collector may spot a jaw while overlooking an individual tooth from a similar jaw.  That bias suggests that the frequency of jaw survival over postcranials or loose teeth is illusory.   Other opinions?

[jpc]

Generally not common here in the Jurassic, Cretaceous and Eocene, but you get into the White River and they are amongst the most common fossils.  Or are they simply more common there because bones in general are more common...no, I don't think so.  In my Eocene, Cret and Jur bone bed sites, a jaw is a good find.    

[Miocene_Mason]

I think one factor is the enamel in teeth is shiny and easy to see, so when the tooth is attached to a jaw it makes the jaws easier to find. Jaws without teeth seem to be found less than those with.

[Wendell Ricketts]

Mostly I think it’s the kind of hyperbole that people engage in when they want to make a joke.  Just to start with, VERTEBRATE paleontology may be the study of teeth and jaws, but it's not accurate to say that’s what all of  paleontology is. I’m also not sure it’s objectively true even within vertebrate paleo. For certain classes of mammals, rodents, lizards, primates, etc., teeth are a lot of what there is just because small animals with less robust bones don’t tend to fossilize, so there are probably more teeth than, say, femurs or metacarpals.  But those aren’t the only kinds of vertebrates that paleontologists study. I also don’t know that jaws are more common than other kinds of bones. (Teeth do sometimes, perhaps often, come in fragments of jawbone, so perhaps that’s what’s being alluded to.)

[Tidgy's Dad]

Healthy jaw bone has a higher average density than other types of dense bone.

http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0088481

This is because it needs to keep all your teeth in place and has to be strong due to talking, biting and chewing.

https://www.livestrong.com/article/333829-how-to-increase-jawbone-density-and-strength/

Shark jaws are also one of the densest parts of a shark's cartilage :

http://www.fossilguy.com/gallery/vert/fish-shark/remnant.htm

More compact, dense bones that have to survive extra stress are more likely to be fossilized (and are harder to eat), so jawbones, tibias, femurs etc. are more likely to be preserved. 

 

 

[Missourian]

I agree.... preservation bias, collecting bias, or a combination of the two. In the Pennsylvanian black shales/phosphatic concretions of my area (Kansas City) jaws and crania seem to be well represented compared with other skeletal elements.

[Missourian]

Ha.... I just now heard someone on the news use the term "jaw-dropping".

[doushantuo]

Your question touches on the subject of taphonomy*,which means i might be back in this thread.

*or biostratinomy/biostratonomy(without arguing the finer points of semantics here,these terms are more or less synonymous;originall coined by Efremov,

the term has fallen into disuse somewhat)

Without trying to be funny: the analogy extends to polychaete(worm) jaws,which can be very common in palynological residues.

But ,the jaws being the only mineralized parts of worms,that is almost self-explanatory 

Meanwhile: 

[Troodon]

Depends what type of critters you are looking for.  They are extremely hard to find where I dig for dinosaurs.  Theropod jaws are thin and just do not preserve very well and are very rare.  The big herbivores are the ones most frequently found often without teeth.  Lack of jaws with teeth one of the big reasons we have trouble describing dinosaurs in many faunas.

[doushantuo]

rhizoturbation:

[Kane]

Just now, doushantuo said:

rhizoturbation:

Not quite seeing the relevance to the original post here. Clarify?

[doushantuo]

I am posting something on mammal jaw taphonomy in a (semi)-arid environment.

 

[Kane]

I'm still unclear how that addresses the initial question about the relative commonness of jaw fossils. Perhaps take the time to explain the relationship here, just to make sure everyone can follow along? 

[doushantuo]

I was thinking along the lines of the different subaerial and subaquous environments possible for skeletal remains to end up in , but for simplicity's sake

just from the viewpoint of biological disturbance. Does the simple fact of preservation equal absence of predators, fungi, bioturbation?

I even agree that posting something about the destruction of a mammal jaw runs counter to the gist of the thread.

 

 

[Fossildude19]

10 minutes ago, doushantuo said:

I was thinking along the lines of the different subaerial and subaquous environments possible for skeletal remains to end up in , but for simplicity's sake

just from the viewpoint of biological disturbance. Does the simple fact of preservation equal absence of predators, fungi, bioturbation?

I even agree that posting something about the destruction of a mammal jaw runs counter to the gist of the thread.

 

 

I think you meant subaqueous?

[doushantuo]

you bet I did . 

Thanks,Tim. I try to keep spelling mistakes to a minimum, but you know how it is.

 

[Fossildude19]

3 minutes ago, doushantuo said:

you bet I did

Thanks,Tim.I try to keep spelling mistakes to a minimum,but you know how it is.

 

I do, indeed.  

[doushantuo]

So it' s a draw?

[Aurelius]

It frustrates me no-end that you get loads of mosasaur jaws from Morocco, but very few skulls. I only have two blocks with any substantial parts of the skull. I've often wondered whether this was collection bias.

[ynot]

43 minutes ago, Aurelius said:

It frustrates me no-end that you get loads of mosasaur jaws from Morocco, but very few skulls. I only have two blocks with any substantial parts of the skull. I've often wondered whether this was collection bias.

99% of those "jaws" are complete fabrications with real teeth added. (Often the teeth are not even mosasaur.)

[Aurelius]

Just now, ynot said:

99% of those "jaws" are complete fabrications with real teeth added. (Often the teeth are not even mosasaur.)

Not the ones I'm talking about