Opalized Fossil Raptor / “Dino” Egg

In the late 1980s, I had blocks of red sandstone crated and shipped back to the U.S. from a Gobi Desert formation. At the time, the people there thought I was a bit slow / crazy in the head to pay good money to export “red dirt rocks.”

Over the decades, I would spend time (when I had some down time) carefully removing the red sandstone matrix to reveal what was inside, which was / is often fossils from around 80 million years ago. I still have around a dozen blocks left to examine - and that should take me through the rest of my life and probably still leave more than half for the next generation.

This particular, Gobi Desert formation turned out to be rich in fossil “raptor” eggs. Prior to the general discovery of the formation in the 1980s, “dinosaur” eggs had been virtually non-existent from the world’s fossil finds.

I suspect that the vivid red color of the sandstone indicates volcanic activity from the period that probably resulted in cataclysmic events instantly burying (and preserving) fauna from that period, by protecting their bodies from scavenging and the natural decay and disarticulation that occurs when bodies of [deceased] living things are exposed.

In any case, this block that I have been “excavating” for the past 20 years, has been turning up these “raptor” eggs. I was working on clearing the sandstone matrix from the one shown above for over a year.

Update: the export of fossils from this region has been banned since the 1990s, when China declared them as “National Treasures” — and imposed the death penalty on anyone caught exporting them! Only the pre-1990s finds are “grandfathered.”

Yesterday, I accidentally broke off a piece from the end of the fossil egg. I was pissed. I had used too much pressure from my air compression tool, after fiddling around with my lab equipment, and blew off the chunk.

After cursing for about 15 minutes and throwing crap around my lab to blow off steam, I set to cleaning and studying the broken away portion. To my amazement, I found an iridescent sheen inside that became vivid in daylight.

The interior of the fossil egg had become “opalized!”

Here’s the other side of the fossil “raptor” egg. Note the unusual, crenelated patterns on the “shell” of the egg. Perhaps these evolved to give the eggs a better “grip” to stay in their nests and not roll out?

Considering how well preserved the shell is, you can imagine how irate I was to goof up and break off a piece of it. However, I do have to say that the opalization exposed is quite the find and well worth the accident that enabled its discovery.

Of course, the temptation is to section through the egg to study or reveal the extent of the opalization. However, I think I will just hold for now and think about it — before doing anything foolish to destroy an 80 million year old, natural wonder.

I believe this to be an egg from an Oviraptor. Above is an artist’s rendition of how an Oviraptor may have appeared.

They existed for some 18 - 19 million years, and likely evolved substantially in that time to develop more bird-like features (such as beaks and possibly feathers) by 70 million years ago.

It is interesting from a timeline perspective, as Archaeopteryx fossils with much more feather development seem to date back, at least from the contexts of their matrices, to 150 million years ago. The Oviraptor evolution to develop features more akin to modern birds seems to be from around 89 million to 70 million years ago.

In any case, to have fossil evidence of their eggs is just spectacular.

Here are some examples (not mine) of other fossils with opalization. The Gastropod and Bi-Valve shell fossils that exhibit opalization are typically the result of castings, where the shellfish encased in the hardened sediment had completely dissolved away, leaving a mold. Silica mineral seeping into and filling the cavity of the mold over eons then form the opalization if they develop a certain, crystalline structure that is refractive.

Here are some more examples. The Therapod tooth at the upper right is formed from a casting. Usually, when the opalized fossil is fully translucent all the way through, it has been formed from a natural casting.

The opalized Ammonite and spiral gastropod shown are opalized only in the layer that would have been just below the surface of the original, mineralized, shell material that typically has to be polished away to reveal the opalization.

This is pretty dramatic. An opalized, fossil casting of the sections of a crab claw and arm. The blue green iridescence of the unpolished fossil is spectacular.

Here are some examples of opalized Belemite (squid) fossils still partially embedded in their white sandstone matrix.

These are more common as far as opalized fossils go, but also among the most spectacular examples when polished, which unfortunately destroys them as fossil records, but converts them to objects of semi-precious mineral splendor.

The example above, shows two different opalizations in the same matrix. The one on the right more as a white opal with lighter overall color with green iridescence, and the one on the left with deeper, fire opal coloration with blue iridescence.