Adulterous Alligators and Romantic Ravens: The Love Lives of Dinosaurs

The social behavior of alligators showed up in the news recently with this article, where National Geographic managed to stay classy by using the phrase “Alligator Baby-Daddies.” Despite this rather questionable choice of phrasing, the article is an enlightening one, informing us of some interesting social behavior in crocodylians.  Alligators, it appears, will seek out the same sexual partners over subsequent mating seasons, although it’s more of an on-again, off-again relationship. They are not monogomous creatures–I’m hard pressed to think of a reptile that is–but male alligators do apparently mate with the same female more or less constantly, even if they aren’t averse to accepting the attentions of others.

While this is a bit unexpected, it’s not by any means new. Crocodiles and Alligators are becoming increasingly known for surprisingly complicated social behaviors. Their nesting behavior is already remarkably similar to birds; the female broods her eggs and guards the nest and young.

So what does this have to do with dinosaurs? Well, Crocodylians are an ancient group. They aren’t descended from dinosaurs; they’re more along the lines of evolutionary grand uncles. They are once piece of a puzzle. To see fill in the rest of it, we need to clamber up the cladistic tree, past dinosaurs, and onto the spreading branches of the great family known as birds. Here we have a remarkable assortment of social and sexual behaviors. Geese that mate for life, harems kept by chickens, promiscous hummingbirds, the forlorn and akward Kakapo (who mates rarely and, it would see, more by accident then anything else), monastic hornbills and finally, the clever Corvids–Crows, Rooks, and the Ravens.

If Crocodylians provide a glimpse at how dinosaurian ancestors paired up and nested, then birds like Ravens and Hornbills give us an interesting look at how dinosaurian behaviors may have advanced in the intervening 65 million years. Ravens are an excellent example. As shown in The Mind of the Raven, Bernd Heinrich’s excellent and entertaining study of Raven social behavior, Ravens mate for life. Crows do as well. And not only that, they raise successive young and are often quite affectionate with each other, spending a great deal of time grooming, caressing, playing, and mumbling with their mates. They apparently show little interest in adultery. Moreover, their interaction with young is an interesting one; while Ravens take care of their chicks and teach them a great deal, they eventually drive them off. Crow Troops, on the other hand, often have large extended families, with breeding pairs helped by succesive generations of offspring.

So. What does this tell us about dinosaurs? Not much–and quite a bit. For one thing, it’s basically impossible to say how dinosaurs behaved during mating (or at least do so with a straight face.) The family we call Dinosauria encompassed a diverstiy of form and behavior that was–and is– truly staggering.  Even within the relatively small group of dinosaurs alive today, the birds, there are hundreds of different social and sexual behaviors. To try and extrapolate the sex lives of sauropod dinosaurs from a hummingbird would be a truly spectacular act of insanity. Form dictates function after all, and the manner in which beasts like Stegosaurus and Triceratopsmated was as much a product of their anatomy and environment as their linneage. (Imagining the difficulty presented by the sharp plated back of a Stegosaurus would give any man pause for thought. Turtles have figured out a rather simple, if long, solution to a similar problem, but that’s an article for another time. )

But here’s the thing; Dinosaurs share several traits with both their crocodylian uncles and their feathery descendents. They nested; we know this because we’ve found the eggs and the nests of almost every branch of their family. They brooded; we know this because we’ve found fossils of that, too. They share a comman ancestry with crocodiles and some of them apparently fed their young after birth. While we can’t say much more then that for Dinosaurs as a whole, we can use what we know about birds to tell us a good deal about the dinosaurs that were most like them: the theropod dinosaurs like T.Rex and Velociraptor. If most birds looked after their young, and most crocodiles gaurded their nests, then theropods likely did things in a fairly similar fashion.

So did Velociraptor mess around? Did Allosaurus live with its inlaws? Did Tyrannosaurs mate for life, or casually hook up? We’ll never know. Sex rarely fossilizes, and despite one graduate student’s quip that he’d “love to find a six footed trackway,” the exact nature of any given dinosaur’s mating behavior is sadly lost the midsts of time.  But by examining the sexual relationships of their relatives–romantic ravens and adulterous alligators, among many, many others–we can gain a precious glimpse of the love lives of Dinosaurs.