Theropod parenting behaviour

Saurophaganax

Hi guys, was just wondering if anyone could enlighten me about the following.

I was wondering, did theropod dinosaurs behave more like birds of prey (a pair bond defending a territory and cooperatively rearing their young) or crocodilians (the female affording her hatchlings a few weeks of protection) when it came to parenting?

To the best of my knowledge, a scan of an allosaurus skull revealed a brain similar to a crocodile, implying that their behaviours were similar, but have there been any more recent revisions or discoveries, particularly in light of the link between dinosaurs and birds?

Thanks

Adam Khor

Saurophaganax wrote: »

Hi guys, was just wondering if anyone could enlighten me about the following.

I was wondering, did theropod dinosaurs behave more like birds of prey (a pair bond defending a territory and cooperatively rearing their young) or crocodilians (the female affording her hatchlings a few weeks of protection) when it came to parenting?

To the best of my knowledge, a scan of an allosaurus skull revealed a brain similar to a crocodile, implying that their behaviours were similar, but have there been any more recent revisions or discoveries, particularly in light of the link between dinosaurs and birds?

Thanks

To my knowledge, there is very little solid evidence of real extended parenting among theropod dinos. I remember Robert Bakker suggested that the high number of juvenile Allosaurus teeth found in some fossil sites along with those of adult suggested the adult Allosaurus had "lairs" and took food back to it to feed their young (I don´t remember all the details of this study, however). As you know, theropods often lost teeth during feeding, like sharks and crocodiles do, but they were quickly replaced by new ones.

Problem is, more recent studies indicate that the Allosaurus probably weren´t parenting after all, but rather gathering in places where there was easily available food- carrion etc- just like Komodo dragons of all ages will gather to feed on large carcasses. And just like Komodo dragons, there's evidence that Allosaurus were cannibalistic, as even some of Bakker's suggested "lair sites" contain fossils of Allosaurus that were eaten by their own species.
There's plenty of evidence of cannibalism among other theropods as well, including tyrannosaurs (Albertosaurus, Tyrannosaurus) and abelisaurs (Majungasaurus), meaning these animals were probably a lot like Komodo dragons and crocodilians in that the bigger ones were always ready to make a meal out of the smaller ones.

Today, Komodo dragon babies and juveniles spend a lot of time up in trees, away from the adults, and only start going down to the ground when they grow a bit bigger and are able to escape more easily.
The fact that juvenile tyrannosaurs, for example, were quite different physically from the adults seems to suggest that they too were filling a different niche, feeding on different prey etc.
Juvenile T-Rex's were not miniatures of the adults like they show you in movies and even documentaries; they were slender, long snouted, with very long skinny legs and able to run very fast. They were probably feeding on small fleet-footed prey and chasing after them, instead of being big game ambush hunters, like the adults were.

Juvenile T-Rex:



Adult T-Rex:



Their long legs and speed may also have been their only defense against adults of their own species...

I think it makes sense that these animals didn´t care much for their young as the difference in size between the babies and the adults would be inmense and it would be very difficult to care for many diminutive young or even, I imagine, to avoid stepping on them...

So in the case of gigantic theropods it may be that they didn´t care that much for their young- they probably weren´t as fiercely protective as the T-Rex in The Lost World, although they may have guarded their eggs like crocodilians do. Whether they cared for the newborn babies at all is, to my knowledge, unknown, as no newborns have been found in any tyrannosaur nests (in fact I don´t think tyrannosaur nests have been found at all).

On the other hand there's evidence that some smaller theropods such as Oviraptor and its close relatives did care for their young and seemingly even fed them while on the nest. Meanwhile, troodontids and dromaeosaurs (raptors) are believed to have been precocial or even superprecocial (able to fend for themselves since the moment they were born) although I'm not sure if there's much evidence about them (I remember reading that one of the clues was the large brain size in troodontid embryos, meaning they were quite capable and alert since the moment they hatched or something like that). There's another small theropod called Scipionyx which was preserved with its guts and within them, there were small bits of food that were supossedly cut into small, easy-to-swallow pieces; however, the Scipionyx was a small hatchling and scientists doubt it was able to cut pieces of meat by itself, so they assume a caring parent may have fed the youngster like eagles and hawks do today. This Scipionyx was, however, able to walk, so it may be that it wasn´t necessarily restricted to a nest, but rather following its parent(s) around like chickens or ostriches do.

So in a few words, it is likely that the extent of parental care varied a lot among the different kinds of theropods, but with most being precocial or superprecocial at least to the best of our knowledge. Ironically, precocial/superprecocial birds in our days are the minority, but I suposse it makes sense since most modern day birds nest in trees or high places (them being able to fly and all) whereas non-avian dinosaurs had to nest in the ground and were constantly surrounded by other, hostile creatures.

Saurophaganax

Adam Khor wrote: »

Ironically, precocial/superprecocial birds in our days are the minority, but I suposse it makes sense since most modern day birds nest in trees or high places (them being able to fly and all) whereas non-avian dinosaurs had to nest in the ground and were constantly surrounded by other, hostile creatures.

Interesting, so do you reckon the development to flight and subsequent requirement to raise young in trees led to the development of pair bonding as in modern raptors?

Adam Khor

Saurophaganax wrote: »

Interesting, so do you reckon the development to flight and subsequent requirement to raise young in trees led to the development of pair bonding as in modern raptors?

Maybe...both parents cooperating to raise, protect and feed the young would be most useful if the young were born helpless and underdeveloped like most modern day flying birds and probably improve their chances of surviving... But that's just a thought.