Bite traces on Late Cretaceous dinosaur bones showing serrated marks. From Jacobsen and Bromley (2009). |
Majungatholus tooth showing denticles and bite traces showing denticle marks. From Rogers et al. (2003). |
Multituberculate gnaw traces on several Late Cretaceous bones. From Longrich and Ryan (2010). |
Azhdarchid pterosaur long bone with tooth embedded (right side, bottom of the bone). Image by Liz Martin. |
Close up of pterosaur bone with tooth emedded and bite traces visible. Image by Liz Martin |
The nature of the bite can also tell us about the nature of the animal making the traces. Most bite traces found in the fossil record are typical of scavenging. They show no evidence of healing, and are often found in areas that wouldn’t typically be covered in bites if it were something like live inter or intra-specific competition such as the ends of bones. However, there are also bite traces in the fossil record that show evidence of healing. A tyrannosaur (Daspletosaurus) shows evidence of several healed bites on its skull, leading the authors to believe this was some kind of intra-specific competition with other Daspletosaurus (Hone and Tanke 2015).
Examples of dermestid mandible marks on Jurassic Camptosaurus bones. From Britt et al. (2008). |
Of course predation traces are not restricted to vertebrates. They are commonly found on things like ammonites, which were often predated on by mosasaurs in the Cretaceous oceans. And of course predation traces or scars are not limited to being caused by vertebrates. Many invertebrates are capable of scarring bones and shells. Dermestid beetles are well known today for decomposing flesh and cleaning of skeletons, but they can also leave traces on the bones, and have been found in dinosaur fossils. Molluscs are known for using their “thorny tongue” or radula to scrape away shells in order to get inside the shell at the animal living inside. These bore-holes are common in modern shells and frequently seen in the fossil record as well. Sometimes these borings are stopped partway through the shell, and considered “unsuccessful”, while they are often termed “successful” as the hole goes through the shell to the unsuspecting clam or oyster within.
In addition to predation traces, there are also several other kinds of marks that can be found on a specimen, including trample traces, transport marks (abrasion, etc.), and other kinds of breakage indicators. This leads to the field of taphonomy, which is basically everything that has happened to an animal from the time it dies to when it is discovered by a palaeontologist. These things tell us about the environment it lived in and aspects of its preservation, and is much to wide of a topic to discuss here. Maybe next time!
Determining the different marks or traces on fossil bones, where they came from, and what other animal may have caused them can be extremely difficult, despite the fact that these marks can be extremely common in the fossil record.
NOTE: Since posting this, Lothar Vallon has pointed out that there is a specific scientific definition for the use of marks vs. trace, in case anyone is wondering why I use trace in most places and mark in others. You can see his comment below!
References
Britt, BB, et al. 2008. A suite of dermestid beetle traces on dinosaur bone from the Upper Jurassic Morrison Formation, Wyoming, USA. Ichnos 15: 59-71.
Currie, PJ, and Jacobsen, AR. 1995. An azhdarchid pterosaur eaten by a velociraptorine theropod. Canadian Journal of Earth Sciences 32: 922-925.
Hone, DWE, and Tanke, DH. 2015. Pre- and postmortem tyrannosaurus bite marks on the remains of Daspletosaurus (Tyrannosaurinae: Theropoda) from Dinosaur Provincial Park, Alberta, Canada. PeerJ 3: e885.
Jacobsen, AR, and Bromley, RG. 2009. New ichnotaxa based on tooth impressions on dinosaur and whale bones. Geological Quarterly 53: 373-382.
Longrich, NR, and Ryan, MJ. 2010. Mammalian tooth marks on the bones of dinosaurs and other Late Cretaceous vertebrates. Palaeontology 53: 703-709.
Rogers, RR, et al. 2003. Cannibalism in the Madagascan dinosaur Majungatholus atopus. Nature 422: 515-518.
Biting traces!!! The terms “traces” and “marks” are clearly defined terms. Marks are produced by pure physical or chemical processes, whereas traces are produced by living organisms actively modifying a substrate (biting into a bone in that case).
http://www.asgp.pl/sites/default/files/in_press_85_2_Vallon.pdf
It is the same kind of mistake as calling a whale a fish…
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Nice to see the bitten azhdarchid bone – on both my visits to the Tyrrell I failed to track it down and see it which was most annoying. Has it turned up again? Maybe I'll get my hands on it one day…
As an aside, I'd add that in my recent paper on bite marks with Darren Tanke we deliberately avoided using the term 'predator' or 'predator-prey interactions' as although these are in really common useage it does imply a very specific interaction (actively killing something) and most of the time we don't and can't know and in others we know such marks are most likely scavenging. It's a bit clumsy, but we use 'carnivore-consumed' so cover this.
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Hey Dave! The azhdarchid bitten bone was on display when I was there, but they took it down for the day for me to look at. The specimen it belongs to is the nicest pterosaur in the collections at the TMP, so I definitely wanted to look at it.
As for 'predator', I stumbled across that problem here as well. I was using predator just as a general 'animal that is eating another animal' mostly, and then realised that doesn't quite work, but by that point I had used it so much and couldn't quite come up with a better term so I decided to leave it in most places. There isn't really another term that covers that, is there?
Anyone else have suggestions on what word to use instead of 'predator' if you are talking about either a predator or scavenger in general – the animal that is eating/biting the other animal?
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Hi Lothar! Thanks so much for the comment. I knew that there were differences in the terms, but not that it was that distinct, as I'm just starting to read up on bites and traces now for a paper I'm writing (and I'm revisiting it after about a year away). I hadn't seen that paper yet, so it's much appreciated! I've updated my post to reflect your comment and hopefully I caught all the mistakes now.
Thanks again 🙂
Liz
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When I was last there, collections said it was on display and the exhibitions people told me it was in the collections. In hindsight it appears that it was in the process of being put on display hence its brilliant ability to be in both places and neither at the same time! 🙂
I think the simple solution is simply to move to 'carnivore' which really only means meat-eating and therefore doesn't distinguish between predation and scavenging. Where you know, or make a case, be specific, but I'm really trying to stick to carnivore in lots of places (e.g. theropods as primarily carnivorous dinosaurs, not 'predatory dinosaurs').
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Thanks for updating (and correcting)! 🙂 All the best! Lothar
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