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RE: Bone-eating (was RE: T.rex was a "chicken")

Bone cracking capabilities also independently developed in two lineages of late 
Cenozoic Canidiae in North America (hesperocyonines and borophagines).  
Interestingly, both lineages also exhibit a zigzag pattern of crystalline 
fibers in the enamel which increased the enamel's strength.  I wonder if any 
theropods had such an enamel pattern?
Guy Leahy

> Date: Sun, 9 Aug 2009 20:11:54 -0700
> From: tijawi@yahoo.com
> To: dinosaur@usc.edu
> CC: qi_leong@hotmail.com; tijawi@yahoo.com
> Subject: Bone-eating (was RE: T.rex was a "chicken")
> Jaime Headden wrote:
>> We assume that carnivores are in fact biting herbivores;
>> this is a given. Bite marks on other bones show this to be
>> the case (as in *Sinraptor* agonistic behavior, a
>> *Triceratops* ilium and sacrum with tooth gouges and holes,
>> etc. What we do not assume here is the particularly
>> intentional habit of taking whole, defleshed bone and
>> processing it orally for the purpose of doing so, which is
>> done by some animals like hyenas and vultures, and some
>> jackals at least. These animals have oral anatomy or
>> behaviors that are specialized to processing the bone or by
>> processing what it within them (like marrow). Hyenas are
>> marrow-eaters, but they aren't particularly delicate about
>> it, and simply crack the bones in their jaws and swallow
>> portions thereof. Few animals are primarily or even obligate
>> osteophages, including deep-sea carcass scavengers like
>> hagfish. When it does occur, it is ordinarily a nutritional
>> issue, and most bone-processing occurs to aquire marrow, not
>> bone.
> Yep, it helps to remember that there are many different behaviors that can 
> lead to getting access to bone marrow. Among extant mammals, specialized 
> osteophagy is apparently quite rare. Hyenas (Hyaenidae) and the Tasmanian 
> devil (_Sarcophilus harrisii_) both have the ability to crack open bones with 
> their jaws, and this behavior requires not only strong dentition, but the 
> ability to resist high stresses at the point of contact between the jaws and 
> the bone. (See: Wroe et al., 2005; Proc. R. Soc. B 272: 619-625).
> As for vultures, I know that the lammergeier (_Gypaetus barbatus_) will crack 
> open bones by dropping them from a great height on to rocks. Their own jaws 
> and feet aren't nearly strong enough to crack open large bones. I don't know 
> how common specialized osteophagy is among vultures (Old and New World). The 
> jaws and feet of many vulture species are even too weak to breach the hides 
> of carcasses; so they either have to wait for a stronger predator to rip into 
> the carcass, or plunge their head deep into an existing orifice. Any orifice 
> will do. Yes, epecially THAT one. It allows read access to the viscera.
> I wouldn't have called hagfish osteophagous (at least not specialized), given 
> that their mouthparts are adapted to feeding upon soft tissue. Hagfishes 
> (Myxini) have been known to enter the bodies of dead or incapacitated 
> vertebrates and devour them from the inside out, either by making use of 
> existing openings (including orifices, in a vulture-like fashion), or by 
> making their own openings.
> And since we're sliding down the animal scale, there is a genus of deep-sea 
> worm called _Osedax_ (also known as a 'zombie worm') that specializes in 
> boring into the bones of whale carcasses. As with specialist bone-eating 
> vertebrates, the aim is to get at the yummy stuff inside the bone.
> Cheers
> Tim