Your Archaeopteryx Questions: Answered! [Pete Larson]

Pete Larson’s new research into the Thermopolis Archaeopteryx specimen currently on display here at the Museum is fascinating (who knew feathers could fossilize?) and we recently hosted an online discussion with Pete to showcase the new findings and give people a chance to get all their burning Archaeopteryx questions answered.

We were so happy to hear the response, the great interaction and the insightful questions asked during the event. Unfortunately, we couldn’t get to them all, so Pete graciously agreed to respond to all unanswered questions in a post here on our blog.The following questions were submitted either during the event itself, or from people who couldn’t attend, in the comments section of the post announcing the event.

And so, without further adieu…your Archaeopteryx questions, and Pete’s answers:

What is your view on the origin of avian flight?

There are two basic hypotheses for the origin of flight: A.) From the ground up – a running start from a fleet footed meat eating dinosaur. B.) From the trees down – theropods climbed into trees and at first glided from tree to tree, to escape predators or to find food. I think that the later idea is most credible. The claws on the hands of early birds, like Archaeopteryx, could have been used, in conjunction with the claws on the feet, to climb into the trees (like juvenile Watsons [sp.?] do today). This also would have limited the stress on the flight feathers and the necessity for a keeled sternum (something that Archaeopteryx does not have).

The Archaeopteryx is angry.
You wouldn’t like him when he’s angry.

What would cause such rapid burial underwater?

A change in temperature could have precipitated the crystallization of tiny calcite crystals that rained down on the organisms. The warmer the water, the more it can hold in solution. Perhaps even daily fluctuations from night to day caused this accumulation over the centuries.

With the great preservation of bones and some soft parts, what was the level of anoxia in the water column?

Because of the reef that protected this “lagoon”, the wave action was limited within the lagoon itself. If you were to measure the amount of dissolved oxygen, you would see a decrease with depth, depleted, at least in part, by resident organisms. Presumably, the bottom was very anoxic, to the point that it could not support animal life. This, however, created a great environment for fossil preservation.

What does the Archeopteryx fossil do for the “evolution of evolution,” . i.e. the progression from Darwin’s theories of natural selection and evolution to modern evolutionary theory to future understanding, both paleo and contemporary?

Soon after its discovery, arguments were made dismissing this discovery as the missing link between birds and dinosaurs. “Dinosaurs do not have feathers (let alone flight feathers), dinosaurs do not have furculae (wishbones), Archaeopteryx does not have serrated teeth (dinosaurs do), etc.”  It turns out that some, if not all, theropods (meat eating dinosaurs) have feathers, including flight feathers. Theropods have furculae (even T. rex). And some theropods have non-serrated teeth, etc.. Archaeopteryx IS the link between dinosaurs and their evolutionary offspring, birds.

In regards to the shark fossil, Hybodus what would be a modern ancestor?

Hybodus is part of the Order Hybodontiformes, of the Superorder Selachimorpha (Sharks). The entire group became extinct at the end of the age of dinosaurs – the KT boundary, 65MYBP.

When you first find these fossils are they of a different color and then change once they hit our oxygen air another wards does our oxygen change these fossil in anyway shape or form?

As one who has collected a lot of fossils from a lot of different localities and ages I can tell you that you often witness color changes. Usually this is due to the drying out of the surface of the fossil (You can test this by licking an unconserved fossil – or even a rock – and see an immediate “brightening” of the colors.) Occasionally a thin white film of gypsum (if there is pyrite in or near the specimen) can grow quickly over the surface of a fossil, literally overnight, that will hide its true color. Atmospheric oxygen is not a big problem, however some fossils, particularly those preserved with unstable minerals near or within can combine with atmospheric water and create such chemicals a sulfuric acid, that can destroy the fossil.

Can you briefly summaries the other fossil evidence for early bird-like creatures other than Archaeopteryx?

We actually have a very good record of fossil birds from a second locality (Liaoning, China where we also find feathered non-avian theropods) that is about 20 million years after Archaeopteryx (Archaeopteryx is 145 MYBP and Liaoning is 122 MYBP) in the Early Cretaceous. [For those of you who wonder what MYBP stands for it is "Millions of Years Before Present", not "Millions of Years before Pete."] Here we see a wide variety of forms, some with more advanced characters and some with very primitive characters, ie. The clawed manus (hand) and toothed skulls persists in some species but have already been lost in others. For the Jurassic, however, diversity was small and all we see are these things we call Archaeopteryx lithographica (but are probably at least two species that some would argue were at least two genera).

Can you see muscle scars on the Archaeopteryx that indicate the presence of muscles which might be used in flight, or are they too small?

Points for insertion of tendons (the tissue that bonds muscles to bones) can be seen on the bones of Archaeopteryx. They do not exactly duplicate what we see in modern birds, But then an animal that lacks a keeled sternum would be built differently then their descendents.

Did you participate? Leave us a comment here to let us know what you thought – and what we can do better next time.

Sad you missed the event? Click here to watch a recording.

Fascinated? Us too. See the exhibit.

VIDEO: Tour the Archaeopteryx exhibit with Pete Larson

VIDEO: Focus on: The Thermopolis ArchaeopteryxF