Friday, August 31, 2012

Sinocalliopteryx gigas: "Get in My Belly"

Stuff just keeps coming out that I can't ignore...

Here is the abstract:

Two skeletons of the large compsognathid Sinocalliopteryx gigas include intact abdominal contents. Both specimens come from the Jianshangou Beds of the lower Yixian Formation (Neocomian), Liaoning, China. The holotype of S. gigas preserves a partial dromaeosaurid leg in the abdominal cavity, here attributed to Sinornithosaurus. A second, newly-discovered specimen preserves the remains of at least two individuals of the primitive avialan, Confuciusornis sanctus, in addition to acid-etched bones from a possible ornithischian. Although it cannot be stated whether such prey items were scavenged or actively hunted, the presence of two Confuciusornis in a grossly similar state of digestion suggests they were consumed in rapid succession. Given the lack of clear arboreal adaptations in Sinocalliopteryx, we suggest it may have been an adept stealth hunter.

Art by Cheung Chungtat, from Xing et al., 2012.

Well a couple things can be taken from this:

1) Dromaeosaurs (i.e. "raptor" dinos) were not always the proverbial kick-boxing ninja super badasses in their respective environments. Remember this is not the first time they have been posited as prey for another dino- the baby dromaeosaur in the oviraptor nest? Indeed the last couple of years has seen a steady diminution of their supposed "hyper-predator" attributes. The clan has gone from JP styled pack hunting predators of larger dinos who killed with disemboweling kicks to solitary hunters of small to medium sized game which was ambushed and pinned down with those raptorial claws.

2) If the stock in raptor dinos has been falling as of late, the compsognathid clan has been quietly rising in the dino-predator sweepstakes. Generally small bodied specialists Sinocalliopteryx gigas was the giant of the family and hints at possibly an unrealized diversity of sizes in this family. And the fact that these dinos are often found with varied, often agile, prey items swallowed whole in their bellies- in this case raptor dinos, ornithiscian legs, and two birdies- says that they were super badasses and quite possibly ninja-sneaky. Don't forget that compsognathids are now thought to be cousins to tyrannosaurids

3) Intraguild predation may have been rampant in theropod dinos. We will talk more about this in upcoming posts but much evidence is pointing to theropods loving to eat other theropods. Intraguild predation is defined as the consumption of a predator who kills another predator that has at least some commonality in prey base. In the above example Sinornithosaurus, the dromaosaur consumed by the Sinocalliopteryx, likely ate a lot of the same prey species- such as the confuciusornis birds in the Sino's belly. By eating a competitor an intraguild predator is both gaining the nutrients from said body but also reducing potential competition for prey, nesting, ambush sites etc.etc.


Xing L, Bell PR, Persons WS IV, Ji S, Miyashita T, et al. (2012) Abdominal Contents from Two Large Early Cretaceous Compsognathids (Dinosauria: Theropoda) Demonstrate Feeding on Confuciusornithids and Dromaeosaurids. PLoS ONE 7(8): e44012. doi:10.1371/journal.pone.0044012

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