Sea Rex 3D swims into IMAX!

Explore an amazing underwater universe inhabited by larger-than-life creatures that ruled the oceans millions of years ago in Sea Rex 3D – now showing in HMNS IMAX!.

Mosasaurus hoffmannii skeleton on display at the
Maastricht Natural History Museum,
The Netherlands

Guided by Georges Cuvier, considered by many to be the father of paleontology, viewers learn about predators such as the ichthyosaur, plesiosaur, and mosasaur. These ancient creatures could grow up to 50 feet and could weigh as much as 15 tons.

Learn about the Triassic, Jurassic, and Cretaceous eras and how life evolved in the deep oceans of Earth. See a mosasaur battle the Great White Shark’s ancestor and witness the mating habits of the plesiosaur.

You’re going to love the film’s time line of the history of the Earth, showing the evolution of the first single cell organisms to the mammals that evolved and began to walk on land. What I found fascinating is the amount of time each of the dinosaurs ruled the world in comparison to humans. Dinosaurs walked the earth for over 160 million years, while humans have only been around for about 200,000 years comparatively.

Evidence of giant marine predators were first discovered in a mine shaft in the Dutch city of Maastricht in 1770, when the partial skull of a Mosasaurus hoffmannii was uncovered. Sea Rex 3D takes you on a journey from the creation of earth until the meteor that killed off 95% of life 65 million years ago. Don’t miss this incredible story about our planet’s history and the monsters that ruled the sea for over 120 million years.

Can’t see the video? Click here.

Sea Rex 3D is now showing in the Wortham IMAX Theater. See show times on our Film Schedule.

Archaeopteryx and Friends

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.

Marine Crocodile
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!

Marine Lizards
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.

Horseshoe Crab
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.

Squids
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.

What a Croc!

Today’s guest blogger is Neal Immega. He has a Ph.D. in Paleontology and is a Master Docent here at HMNS. In his post below – originally printed in the Museum’s volunteer newsletter– Neal discusses the Geosaurus, a fossil featured in our exhibition Archaeopteryx: Icon of Evolution.

The Houston Museum of Natural Science has a new exhibit, “Archaeopteryx: Icon of Evolution” that features the best Archy ever.  Do not let that blind you, though, to the other critters on display. One of these is the best marine crocodile anywhere, a Geosaurus with an exciting evolutionary story all its own. These animals have a worldwide distribution from Brazil to Germany, but this specimen is the most complete, and shows the soft parts. Ah, the preservation of fossils in the Solnhofen limestone is amazing.

Let’s see what observations we can make from the skeleton and what conclusions we can draw. Look at this picture and get an overall impression of the fossil. The label says it is a croc, but is it? It does not look like any croc I have ever seen.

Complete Geosaurus skeleton, with skin impressions, from the Solnhofen limestone.
Geosaurus skull showing croc dentition

Head: The front end certainly looks like a modern crocodile head. The teeth are conical and striated, with the typical croc dentition:  teeth are located inside and outside the jaw line, and there are large teeth half way down the jaw.  Modern crocs use them for breaking turtle shells (see the YouTube video referenced below).

Tail: Ok, so it is a croc but it does have a very strange tail. Let’s look more closely at the tail to see if there is any support for the decision the preparator made to indicate a tail like a shark’s.

The faint skin impressions support
interpretation as a shark-like tail.

The discolored rock strongly suggests that the tail does have a shark outline, unlike that of all known modern crocodilians. Even better, compare the caudal processes (bumps on the top of the vertebra) in the area of the fin to those farther up the spine.  The processes in the tail fin area are longer and reverse orientation: they point toward the head, possibly as support for the fin. The fin is real!

Armor: This croc does not have any! There are no osteoderms (bony plates inside the skin) anywhere. The osteoderms in modern crocs do not provide complete coverage and thus are not much use as armor; however, a modern croc has muscles between its osteoderms that can stiffen up the skin during rapid land movements.  Apparently Geosaurus got along without them.

Legs: The arms are very short in proportion to the legs, quite unlike modern crocs.

Salt Gland: Many animals have glands to secrete sodium chloride because they live in or on life from the ocean and eat way to much salt. This animal is said to have chambers in the skull for a salt gland, but I cannot see it. I guess I will take their word* for it. A modern croc has a salt gland in its tongue while many birds have theirs in the skull.

Analysis: Modern crocs are slow swimmers and, thus, ambush predators. A shark-like tail suggests this was a higher speed predator. A modern croc has about 5% of its weight in osteoderms and their absence would improve the water speed at the expense of land speed. I think we have caught this croc species in the transition stage of becoming a true marine predator. It still had clawed limbs to crawl out on the land (to mate and lay eggs) but their smaller size would certainly help reduce drag. If this evolutionary path had continued, the croc’s descendants might have ended up looking like Ichthyosaurs, air-breathing reptiles that gave live birth and looked remarkably like modern dolphins. Remember, a saltwater croc in Australia is called a marine crocodile, but it does not have many adaptations to live in the marine environment besides a salt gland in its tongue.

An Ichthyosaur is a reptile completely adapted to a marine environment.
What happens when a Steneosaurus trys to
ambush an Allosaurus at the water hole

There are other crocs found in the Solnhofen limestone, including long-legged land crocs, dwarf ones, and a substantially armored one, Steneosaurus, featured by Dr. Bakker in this wonderful drawing.

To read more about the Geosaurus, check out Dr. Bakker’s blog.

References:

Wikipedia:  Criosaurus , Dakosaurus, Geosaurus
A nice discussion of aquatic crocs is at  http://en.wikipedia.org/wiki/Cricosaurus

Modern croc using those teeth on a turtle: “ahmedsadat” posting on YouTube, 2008, “Crocodile eats turtle”,  http://www.youtube.com/watch?v=cSKAXOFvi6c

*Salt glands – it is claimed that the skulls have a chamber for salt glands see Fernández and Gasparini, 2008, Naturwissenschaften. 2008, 95(1):79-84. Epub 2007 Aug 22. http://www.ncbi.nlm.nih.gov/pubmed/17712540

Dwarf crocs from the Solnhofen limestone, page 36 in Wellnhofer, 2009, Archaeopteryx, Icon of Evolution, Verlag Dr. Friedrick Pfeil.

All pictures by Neal Immega except the Dino/Croc fight which is by Dr. Bakker.