Birds and Dinosaurs as Good Dads

 

Dino dads may have tended nests with the eggs of several females. Illustration by Bill Parsons

 

Despite our fondness for the image of the mother bird lovingly perched on her nest, a new study from Science argues that, for the earliest bird species, the dads were the original caregivers.  Stranger still, birds seem to have gotten their good daddy behavior from dinosaurs.  

The study comes from David Varricchio of Montana State University and colleagues, and it’s based on close examination of adult bones found around dinosaur egg nests.  Exclusively paternal tending of the young may have evolved for a reason familiar to anyone who has spent time around a pregnant woman:  Forget the kids, the females needed to focus all their attention on eating, because of  the heavy energy demands of knocking out one big egg after another.   

For dinosaurs dads, fatherhood “was more than just looking macho and gnashing teeth,” writes Richard O. Prum in a commentary on the new study.  He also relates a sad story about  how some dads can’t catch a break when all they want is to help take care of the kids:

In 1924, [American paleontologist Henry F.] Osborn named a Cretaceous theropod Oviraptor, or “egg seizer,” because it had been fossilized in the very act of robbing [a] dinosaur egg nest.  In 1995, new specimens showed that Oviraptor was not stealing those eggs but caring for them and possibly even brooding them …”

Males still contribute to care of the young in 90 percent of bird species. That may not sound like much, but it compares to just 5 percent of mammals.  Only about 100 bird species, including ostriches, emus, cassowaries, and kiwis, still rely exclusively on paternal caregiving.  These Paleognathes are the basal lineage of modern birds.  That means they came first, and the system of both parents caring for their nestlings evolved later.

Prum calls the new study “revolutionary” and speculates that researchers may soon also track the origins of birdsong back to dinosaur ancestors.