Corpse Flower Watch: Day 12

Today, Lois measures just about 64.25 inches. Her vertical growth has slowed to only .75 inches since yesterday – this, plus the bright purple streak that appeared on the her right side and the fact that the bracts have fallen off completely (see image below), indicate that blooming is imminent!

And, we have some great news! The Cockrell Butterfly Center will be open around the clock for the Corpse Flower Watch until after Lois has bloomed – come by any time to see her! You can get tickets here.

7.12.10 Amorphophallus titanum
The bracts have fallen! See a full set of photos of the
Corpse Flower’s growth here.
Date Height
July 1 31″
July 2 34″
July 3 37″
July 4 41″
July 5 45″
July 6 49″
July 7 53″
July 8 57″
July 9 60″
July 10 62″
July 11 63.5″
July 12 64.25″

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

The Animals of Solnhofen – Geosaurus

Our Archaeopteryx show has bedazzling fossils – the only Archaeopteryx skeleton in the New World, complete with clear impressions of feathers. Plus frog-mouthed pterodactyls, fast-swimming Sea Crocs, and slinky land lizards. Today we learn about the Geosaurus.

Geosaurus – Shark-Tailed Sea Croc
Speediest of the ocean-going crocodilians

Some creatures of the Late Jurassic lagoon were up & coming evolutionary clans – the teleosts, for example, were just beginning their takeover of the marine ecosystem. Other groups were Darwinian ultra-conservatives, living fossils in the Jurassic, changing slowly or not at all. The Chimaeras are a fine example.

And then there were a few very special cases – Late Jurassic critters that had reached the apogee of Natural Selection, the highest development of their race. Best representative of this phenomenon:

The Super-Swimmer Croc, Geosaurus.

The earliest crocs of the Triassic were land animals, roughly fox-sized with long legs. In the Early Jurassic, crocs went into rivers and lagoons.  That’s not a surprise. All living crocodilians swim well in freshwater, and a few – the Florida Croc and the Australian Salt Water Croc – will go out beyond the surf and navigate between oceanic islands.

But…..no modern-day croc is super-specialized for life in the high seas. None have the double-lobed tail of the sort we see in big, fast sharks, like the White Shark. Open-water sharks have a characteristic double-lobe tail. The vertebral column takes a sharp bend upwards to support the upper lobe of the tail. The lower lobe is made of tough skin and connective tissue. You can see the double-lobed tail configuration in our Archaeopteryx show in the hybodont sharks, a family common in the Jurassic.

To compete with such speedy sharks, a croc would have to evolve a double lobed tail. No crocs did – except one extraordinarily graceful clan, the geosaurs.

Our exhibit is graced with one of the finest geosaur specimens ever dug. This awesome Solnhofen skeleton demonstrates how evolution had transformed a “normal” river & lagoon crocodile into a reptilian torpedo, an open water predator that matches a shark in efficiency.

Geosaur evolution made a sacrifice unusual among the crocodilians – it traded in armor for velocity. All early crocs from the Triassic  and earliest Jurassic had thick bone plates over the back and neck and all over the throat and belly. All modern day crocs too carry extensive armor plate. This armor is useful when crocs are attacked by land predators or by other crocs. Most of the sea-going crocs of the Jurassic and Cretaceous kept some armor. Case in point: armor was carried by the teleosaurs, big  sea-crocs who were the apex predators at Solnhofen and most other sites in the Mid and Late Jurassic.  There is excellent evidence that large Jurassic dinosaur meat-eaters did indeed attack teleosaurs.

The geosaurs went a different way. They went skinny-dipping.

Geosaur skin was totally devoid of bone armor plates. They were naked. This development made the geosaur body lighter and more flexible.

Fast-swimming demands a specialized flipper for steering. The “normal” croc has long front legs and very long hind legs. The hind legs have wide webbed feet and assist the tail in propulsion underwater. All modern crocodilians and most fossil species keep this arrangement.

The geosaur limb equipment evolved in a unique way. Those long, strong hind legs were retained. But the fore-limbs were transformed into short flippers that worked like the diving planes of a submarine. No other croc clan did this with their front limb.

Impressive….but the outstanding geosaur specialization was the tail. “Normal crocs” have a deep, strong tail that bends down just a little bit at the end. The geosaurs went far beyond “normal” – they evolved a tail almost identical in profile to that of a modern tiger shark or a Jurassic hybodont. The geosaur tail possessed  two lobes, one bigger than the other in shark-fashion. 

Take a good look at our geosaur…..notice something strange?

The tail is upside down!  The vertebral column bends down, not up the way it does in sharks. Mummified geosaurs show that the upper lobe was made from tough skin and connective tissue, just like the lower lobe of sharks. The hydrodynamics of the upside-down tail worked just as well as the right-side-up shark tail.

Here’s a wonderful example of how evolution works: Natural Selection is opportunistic. It operates on what is already there. “Normal crocs” already had a slight down bend of the vertebral column.  For “normal crocs” to evolve a right-side-up version of a shark tail was almost impossible. But evolution took the simpler path by emphasizing the downward bend and then adding the upper lobe.

No croc of any age matched the swimming efficiency of geosaurs (although the Cretaceous Hyposaurus, from my home state of New Jersey came close). Most other croc groups are distant seconds. Therefore, the Late Jurassic was the high point of croc-natatory prowess (look it up;  “natatory”, a good adjective).

Why? Why didn’t some later croc group evolve upside-down shark tails as specialized as those of geosaurs?  We don’t know. My guess is that sharks evolved so fast in the Cretaceous that crocs were pushed out of the open-water/fast-swimming niches.

One more thought – geosaurs probably had to crawl onto sandy beaches to build nests and lay eggs. Their tiny flipper-like fore limbs would have been a big disadvantage – mom geosaurs must have been far more vulnerable to land predators than “normal crocs.”

Focus On: The Thermopolis Archaeopteryx [Pete Larson]

The Thermopolis Archaeopteryx is one of the finest examples of this species ever discovered. And, lucky us! Paleontologist Pete Larson stopped by to tell us what makes this fossil so special, and fill us in on his new research on it – see what he had to say in the video below.

We’re talking dino-bird with Pete Larson, tomorrow morning at 10 a.m. Central. Check out our previous blog post for details on how you can participate!

Or, check out the Thermopolis Archaeopteryx for yourself! Visit Archaeopteryx: Icon of Evolution at HMNS through Sept. 6, 2010.