Dinosaur eggs are, sadly, very often for sale as they don’t seem to attract the attention of the law in the way in which bones do (that and the fact that they are obviously easier to fake). But what fascinates me about them is the monotonous regularity with which they are identified as belonging to specific taxa. Quite a few people seem to be under the bizarre impression that you can diagnose the family or even genus of dinosaur that laid an egg based on, well, I’m not sure what, but I’d guess the size and shape.
The truth is of course that to look at, most dinosaur eggs are not really any more diagnostic than those of living birds. Some do have distinctive proportions or textures, but mostly they are much of a muchness, and there seems to be quite a lot of variation present, even within single species. Unless you find an embryo inside (or even the egg inside an adult), a brooding parent on top, or can get a sample under the microscope (and match it up to those for which embryos are known) it’s really quite hard, if not impossible, to tell what might have come out of any given egg. Thus, while we do have vast collections of dinosaur eggs, what actually laid them is, in most cases, a mystery for now at least.
I had the fortune to spend some time with an expert on dinosaur eggs when out in Henan a few years back. After some scrabbling in a very productive egg locality I had fished out something like ten very different looking pieces with a variety of curvatures, thicknesses, and ornamentation on both the inner and outer surfaces. On asking I was told that none of them were diagnostic beyond one that ‘might belong to a theropod’.
More and more work is revealing which eggs likely below with which clades or more specific taxa, but the number of times I have seen a random egg or nest listed as belonging to a ‘sauropod’ or ‘hadrosaur’ or still more unrealistically ‘Tyrannosaurus’, is really quite unnecessary. In the case of people selling eggs it’s obvious that they want to increase the value of the material by putting a familiar name to the specimen, but the implied accuracy is nonsense. A little more depressing, I’ve seen a few museums try to pull off the same thing on eggs they can’t possibly have identified.
While it’s nice to poke fun and incompetent fossil dealers who are passing off illegally acquired material, there is a more general lesson here. For all that we do know about dinosaurs, there is, naturally, quite a bit we still don’t know. There are also areas that are often overlooked or neglected and personally I’d put dinosaur eggs into that category. There is a lot more information that can be gained from these once we can match more of them to their ‘owners’ and this and certainly will reveal more secrets in the future.