Pterosaur Bone Swallowed by Velociraptor

A recent blog post by Dr. David Hone featured the subject of his team’s latest paper, Hone et al. (2012), an azhdarchid pterosaur bone found within the chest cavity of a well-preserved, 3-D specimen of Velociraptor from the Late Cretaceous. The bone specimen was lodged high in the chest of Velociraptor (close to the spinal column, probably in the proventriculus, a portion of the esophagus between the crop and gizzard). The bone is flattened but tubular with only 3/4 of the circumference preserved (see closeup here). Scale bars indicate the long diameter of the extremely thin-walled bone was ~1.2 cm in length with broken eroded ends and a few splinters. The preserved length was ~7.5 cm.

The pterosaur bone lies inside the torso of Velociraptor.

Figure 1. The pterosaur bone (in pink) lies inside the torso of Velociraptor. Broken rib (blue), sternal plates (yellow), coracoids (green) and scapula (brown) are colored.

Dr. Hone reports, “As you can see the bone is incredibly thin-walled which is the major reason that it’s inferred to be an azhdarc[h]id pterosaur, though their presence in the Late Cretaceous, including a related formation, and the general absence of other pterosaurs in the Late Cretaceous helps support this identity.”

Inferences
The next day’s blog by Dr. Hone included some inferences drawn from the association of the bone within the gut. “Moreover, the azhdarchid in question was most likely 9 kg in weight with a 3 m wingspan (and could have been considerably larger), while the Velociraptor was a sub-adult of around 13 kg…It’s more likely this was a young carnivore scavenging on the carcass of a dead pterosaur, as indeed was inferred for a similar previous specimen from Canada.”

Which Bone is It?
Unfortunately the pterosaur bone was not identified by Hone et al. (2012). It was likely a section of the wing due to its circumferential shape, length and straight long axial shape. The leg bones would have been rounder. With the process of elimination we note there’s not much meat on the metacarpus or wing finger. There’s more on the ulna+radius  and even more on the humerus. We might expect more shape changes on the humerus. The ulna would have been deeper in cross-section. So the bone is likely a central portion of the radius. (If there’s a better guess out there, please let me know!)

Zhejiangopterus

Figure 2. Zhejiangopterus, a Late Cretaceous azhdarchid pterosaur that is the right size and the right age to match the pterosaur radius found within a Velociraptor specimen. Click for more information.

Which Pterosaur Is a Good Match?
Zhejiangopterus is a Late Cretaceous azhdarchid pterosaur from China that is the right size and the right age to match the pterosaur radius found within a Velociraptor specimen. The radius would have had muscle/meat on it, so would have been a better choice to eat than any of the more distal wing elements.

Was Velociraptor a Scavenger or Predator?
Dr. Hone provides some clues in his popular blog. Hard to tell. Too hard to guess. Was the prey item dead or alive to begin with? Does it matter?

As always, I encourage readers to see specimens, make observations and come to your own conclusions. Test. Test. And test again.

Evidence and support in the form of nexus, pdf and jpeg files will be sent to all who request additional data.

References
Hone DWE, Tsuhiji T, Watabe M and Tsogbataar, K. Pterosaurs as a food source for small dromaeosaurs. Palaeogeography, Palaeoclimatology, Palaeoecology, in press. online abstract and figures.

About these ads

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s