Friday, January 27, 2012

Massospondylus Babies: Old Eggs, New Find

A nesting site of the Prosauropod Massospondylus

"New discovery: Oldest nests and embryos discovered in South Africa" When I first read the title of the article I immediately knew what they were talking about. The article was referring to the discovery of fossil dinosaur nests and eggs belonging to the Prosauropod dinosaur Massospondylus, a plant eater that's line was among some of the first giant herbivores in the history of life on earth.

These nests weren't new to the scientific community though, the first Massospondylus eggs ever found were unearthed in 1977, and thirty years later in 2007 we finally had the technology to be able to break into them and examine the tiny embryos. The eggs and embryos date back to 190 million years ago during the Jurassic Period, making them the oldest fossil eggs on the planet. Now with more recent expeditions we have uncovered about 10 more nests filled with up to 35 eggs with embryos. We've hit paleontological gold!

The embryos house some interesting little surprises. The skulls of the juvenile Massospondylus are disproportionately large, and the neck, unlike their parents, is actually quite short. The eye socket is also very large, something seen in young animals today, and the front and back legs were of equal length, unlike adults which have short front legs and long back ones. This suggests that the juveniles were quadrupedal and grew to become bipeds.

However, what's most surprising is that the Massospondylus embryos have no teeth. This was unexpected, as the juveniles would need teeth to feed themselves to fuel the growth of their bodies. This indicates that the young were dependent of the parent for food, meaning Massospondylus exhibited parental care and fed the young after hatching, at least until their teeth grew in.



  1. Fascinating find, RaptorX. Wondering...if the embryo showed no sign of teeth, once it became a hatchling, do you think its parent might have fed it in a similar way as birds feed their young today? For instance, is there any evidence to suggest the parent might have chewed and regurgitated food into the hatchling's throat so the baby could eat, as without teeth it could not chew?

    1. Yes I do actually, although adult prosauropods couldn't chew either. Their teeth were peg-like and not good for grinding, and their small heads also lacked the muscles for chewing, but I still think it's plausible.

      The way modern day birds transfer food to their young is through a pouch in the throat called the crop. For a long time it was thought that birds evolved this trait in later Theropods, like Dromaeosaurids, and thus more primitive prosauropods lacked it. However, recently a mummified hadrosaur named Leonardo was found to have a bird-like crop inside its throat, pushing the structure back to the base of an entirely different branch of the family tree of dinosaur.

      Since Leonardo had such a bird-like trait, it seems safe to assume that at least prosauropods had some form of crop as well. It could've also been helpful to have, as the crop is also used in birds to store food prior to digestion.

  2. Fascinating! I had no idea, but seems like a logical assumption. Glad you found some evidence to support that notion. Thanks for your thoughtful reply.