STL Science Center

STL Science Center

24 July 2011

Case for Solitude

There isn't much family fun related traffic on the internet for Balaur bondoc. This isn't because the animal is unpopular it is simply because it is so new to science. Therefore, considering that we will not have much to talk about in that vein today, let's look at the uniqueness of the skeletal remains that have been uncovered. The obvious place to start is at the toes. The first and second digits of the feet are extended in a way that we see in other dromaeosaurs on only the second digit, the first (or fifth depending on the source) being behind the leg present as a dew claw sort of arrangement. The third and fourth toes bear the weight of the animal. In B. bondoc the animal possesses killing type claws on both the first and second toes held retracted and available in different arcs or areas of attack for either the functions of slashing or grasping prey. The exact nature is, of course, still debated.

Going up the leg we have the unique femoral and pelvic muscle attachment spots on this animal. Like its cousins the velociraptors this animal had strong legs. However, in velociraptor those legs were strong and the muscle lean and lithe while being strong enough to use its second toe for offense thus enabling it to also run at a fair clip over distance. B. bondoc, however, has deep musculature attachment sites for its quads and hamstrings that are much more indicative of kicking and pounding strength than of possessing speedy muscles. Think of B. bondoc as the Bruce Lee of the dromaeosaurs; it can knock out heavy prey with a strong kick, and with the twin claws the kicks are even deadlier, but its cousins were built more for speed than brute force.

It has been therefore thought that this animal may have hunted alone despite its small size. Of course, we then have to take into account why it was so small yet clearly successful enough a predator to evolve and survive. The key to this is looking at its habitat and what behavioral clues we can find in the fossil record. There is evidence of the other small dromaeosaurs, like velociraptor and microraptor, becoming stable hunters and successful animals in their environments due to their performance within their niche of their world and there is evidence for their behaviors within their fossils as much as there is sure to be evidence in these fossils of some of the behaviors of this animal. Back to topic, being a small, solitary, hunter in the world of velociraptor would not have worked out well given the sizes of its contemporaries and microcraptors probably lived in small units for hunting and safety as well given their contemporary world. How can we then believe that the small Balaur would also then be successful but could have lived alone? The answer is in the habitat.

Remember that B. bondoc was found on the Cretaceous island of Hateg or the land representing it leastways. This island was thought to be about the size and shape of Hainan off the coast of China making it about 12,000 square miles in size and it was probably heavily forested. Island and heavily forested are the first clues to the success of a solitary yet small predator. Undergrowth and the exclusion of the island from the mainland would immediately lend themselves to the benefit of a small hunter. Also, consider the prey that would be found on an island. An Iguanodont or a Sauropod can grow enormous on the mainland, but on an island both space and food sources are highly limited so that, over time, if a species does not adapt to available food, in this instance by not growing as large, they are bound for extinction. Smaller prey means predators would have to actually grow smaller also or risk eating up all available food sources too quickly to survive and smaller prey would also benefit from thick undergrowth in the same way a smaller predator could.

In summary; smaller prey, easy concealment in thick undergrowth, strong heavy-handedness in attack capabilities, probably a good sized brain, twice as much weaponry on its feet, and exclusion of mass competition probably spelled apex solitary predator for B. bondoc. Time will, however, tell and perhaps larger predators will be wrested from the earth on that island. Until then I find solitary behavior just as plausible as the "Raptor Pack" mentality for this species on this island.

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