Archaeopteryx and Friends
A virtual visit to a Jurassic wild animal preserve
By Neal Immega, Paleontologist
Is it a bird? or a dinosaur? Archy is both. We have the best-preserved Archaeopteryx on display in our basement and you can see all sorts of significant evolutionary developments such as a semi-lunate metacarpel in the wrist, hallux to the side, elongate tail, furcula, a large second digit claw on the hand, a sternum without a keel and all sorts of other highly abstract features that confirm that Archy is both a bird and and a dinosaur. Come and see me and I will debate both sides of the question until you run screaming out of the room. There are literally oceans of virtual ink written about this critter.
BUT WAIT, we have so much more. I want to introduce you to some of the other things that we have that are really significant and just plain cool.
|Geosaurus – A Marine Crocodile with a shark like tail but still has legs.|
I know that you are thinking about salties (crocs living in saltwater) down under, but you are still thinking within the box. Envision an island with limited species living on it, protected from outside influences by a deadly ocean. Species would evolve to fill every available niche, just like the kangaroos in Australia occupy all the herbivore niches from squirrel to sheep but are still recognizably ‘roos. What would a croc look like if it evolved to take over the role of a marine predator? It could look a whole lot like an Ichthyosaur (see the one in the paleo hall by the freight elevator). Amazingly enough, we have caught it part way through the process of adapting to sea life: it has limbs even though it also has a shark-like tail. I wonder if we will ever find a croc without legs that gave live birth and thus never left the water. What an amazing mix of characteristics!
Consider a hypersaline sea that was so toxic that anything that fell in it died and was preserved perfectly because there were no bottom scavengers. Lizards seem to be able to live under the very harshest conditions, but there is only one type on this island. The last surviving remnant of this group is the New Zealand Tuatara, a very strange beast. It has a double row of teeth on the upper jaw and a single row below. The teeth are just projections of the jaw bone. Another feature that can also be seen in fossils is there is a hole in the top of the skull for a “third eye.” Today, the third eye is non-functional, but I bet it was in the far past. Our exhibit has a whole collection of these lizards that lived on land, and they look a lot like modern lizards. BUT, there are also two specimens with vastly more ribs and tail vertebrae, as if the creature occupied the niche of eels, but eels with legs! This is another transitional form, adapting to marine life but retaining some of the features of land animals.
|Tuatara family lizard living on land|
If you look at the specimen in Room 13 with a magnifier and a light, you can SEE the place where the third eye was.
We can make up a story about our horseshoe that’s so sad that you will want to cry. Envision a little horseshoe crab bumbling around the shallow water eating little things from the mud. A wave crashed in and washed the crab out beyond the fringing reef of the Solnhofen sea. The crab landed on the bottom on his back (it swam top-side-down), struggled to turn over and made marks in the soft sediment. The crab was very tough but the environment did not provide any oxygen and the hypersaline water burned its gills. It tried moving, but things did not get better. The current rolled some empty ammonite shells on the bottom, making tire track-like track marks. The crab turned again, and things did not get better. The crisp mark made by its dragging tail became a dashed line on the bottom as it tried to swim out of there, but it could not. Finally, it stopped trying, and died. Today, we can see the whole narrative on 30 feet of rock.
Normally, paleontologists do not find much evidence of squids because they do not have many hard parts. The Solnhofen seabottom, however, preserves nearly everything. One fossil has a long cuttlebone-like internal shell stiffening its soft mantle tissue “wings” on the outside.
Another of the squid fossils shows hooks on its arms - that show up as lines in the tentacle area - for snagging prey. It even has a modern relative that was given the extreme name, Vampyroteuthis infernalis, or Vampire Squid from Hell. It dives thousands of feet down in the sea, is red in color, has huge blue eyes and use photophores to confuse preditors, but it is only a few inches long and eats shrimp.
|Squid show its pen and soft parts|
These are only a few of the more spectacular fossils on display in Archaeopteryx: Icon of Evoloution. There are many reasons why Darwin loved the fossils from the Solnhofen. Take a walk with a fellow docent or download the guide to the hall from the Guild’s digital library and see what you can find. CAREFUL! If you show any interest, we will tell you enough things about the hall that you will become addicted and start giving tours.