Monday, April 30, 2012

April 25, 2012. Thermopolis, Wyoming. The Dinosaur Museum.

We're in Thermopolis, Wyoming,
home of the world's largest mineral hot springs.
Just a stopover on the way to Cody.

We checked out the Wyoming Dinosaur Center,
a 16,000 square foot complex in the Big Horn Basin of central Wyoming.
The Dinosaur center includes a world-class museum,
working dig sites, and a complete modern preparation laboratory.
Dynamic displays feature dinosaurs 
from all around the world.

Between 65 and 145 million years ago
during the Triassic, Jurassic, and Cretaceous periods,
dinosaurs walked around Thermopolis.
The Museum houses over 30 mounted dinosaurs,
a modern preparation laboratory
and hundreds of displays and dioramas.
The collection includes fossil fish from Scotland,
flying reptiles from Brazil, marine reptiles
from Russia and Switzerland,
and fossil dinosaur eggs from China and Argentina.

Hypsilophodon is named after the teeth in the front of its mounth.  Many scientists believe it was a herbivore but some contend that it ate meat, at least on occasion.   The teeth are set deeply into its mouth and this strongly implies the presence of cheeks.  The large eye sockets tell us it likely had good vision and may have even been nocturnal.  Fossil evidence also implies that it was a herding dinosaur since it is usually found in groups.  Most specimens are found in Southern England but they can also be found in Portugal as well.

Triceratops horridus
Triceratops was the largest and last surviving horned dinosaur.  It grew as large as a male African elephant.  Despite its size, some scientists think it could have achieved a slow, rhino-like gallop, perhaps as fast as 25 miles per hour. 

Tyrannosaurus rex - 40 feet long -  5-6 tons
Tyrannosaurus was one of the largest mest-eaters to walk the Earth.  Scientists still disagree how fast it was, though 25-30 miles per hour does not seem unreasonable.  At that speed it could run quicker than all but the fastest human sprinters.  More importantly, it clearly was built to move faster than Triceratops and other potential prey animals of the Late Cretaceous.
New evidence from close relatives Tarbosaurus from Asia and Albertosaurus from Canada suggest the Tyrannosaurus hunted in packs.  If you think imagining one T. rex coming after you is scary, try imagining a dozen of them.  Because prey such as Triceratops was so dangerous, Tyrannosaurus probably preferred scavenging carcasses, or hunting the less dangerous duck-billed dinosaurs in its environment.  When it did hunt horned dinosaurs like Triceratops, it would have tried to startle them into fleeing, letting Tyrannosaurus land a bite to the unprotected rear.
A single T. rex bite could have gouged out a wound 3 feet in length, a foot wide, and a foot deep.  Such a blow would have killed any animal of the time.

The T. rex in front of you is named "Stan."  Stan was found by the Black Hills Institute in South Dakota.  The Black Hills Institute are the people who found "Sue" as well.  Sue is one of the largest and most complete T. rex in the world.  Stan is not the largest specimen, but it is very complete.  
The media has carried claims that Tyrannosaurus did not kill its own food, instead scavenging for every meal.  Few scientists take this idea seriously.  Of course most meat-eaters scavenge when they are lucky enough to find a dead animal, but there is rarely enough dead meat lying around to scavenge all the time.  That is why only vultures and other flying animals are full time scavengers; not only can they see father, but it takes less energy to glide that it does to walk.

Many people imagine that all dinosaurs lived at the same time.  In fact, dinosaurs ruled the Earth for 150 million years.  Individual species of dinosaur only lived for 3-5 million years.  Of the circa 2000 kinds of dinosaur known, only a few dozen existed at the same time as Triceratops and Tyrannosaurus.  Tyrannosaurus and Triceratops lived at the very end of the age of dinosaurs, between 68 and 65 million years ago.  65 million years ago something happened that killed off all the dinosaurs (except birds).  Scientists do not fully understand what killed the dinosaurs, but the impact of a large comet or asteroid in the Gulf of Mexico is widely agreed to have played a large role.  Examination of rock layers shows that an inland sea was raising and lowering, occasionally covering central North America.  The constant shifting of the environment would have stressed the animals at the time.  Recent research shows that the Hell Creek Formation, where Tyrannosaurus and Triceratops are found, underwent a large turnover in plant types.  Perhaps a combination of environmental stress and the impact were needed to kill off the dinosaurs by the time the Fort Union Formation was deposited.

A duck-billed dinosaur called Maiasaurus tends to a nest of babies.
How do we know these dinosaurs took care of their young?
In the early days of dinosaur research, nothing was known about the family lives of ancient dinosaurs. In the 1920s, an expedition to Mongolia was the first to unearth fossilized nests of dinosaurs.  Clutches of eggs were laid in hollows in the ground.
But still, little was known about how these dinosaurs grew up.  Then, in the 1970s,
more dinosaur nests were found in Montana, in a place that is now called Egg Mountain.  Most of the nests were Maiasaurus nests.  Adults, hatchlings, older juveniles, and eggs are all known from the same area.
This nesting area preserves evidence that helps us understand how dinosaurs lived.  Fossils of hatchling Maiasaura, still living in the nest, show wear on their teeth from grinding plant material.  This suggest that their parents were bringing food to their babies. For this, the animal was named Maiasaura, which means "good mother reptile."
Since Maiasaura nests were found, other fossilized nests have been found as well.  One nest from Mongolia has a parent dinosaur's skeleton sitting on top of it.
Eggs are now known from most major groups of dinosaurs.  As far as we know, no dinosaur gave birth to their young.  Since dinosaurs hatched from eggs, this means that they all began life very small.  

Maiasaura peeblesorum
Maiasaura was discovered in Montana in the 1970s.  One site contained a mass of jumbled bones;  it was thought to be the remains of a herd of maiasaurs.  Early estimates put the number of animals at more than 10,000 animals.  Recent estimates have raised doubts about the number of maiasaurs, but the evidence still suggests that Maiasaura lived in large herds, perhaps numbering in the thousands.  This may sound like a lot of dinosaurs, but modern plains animals migrate in large herds today. 
Maiasaura is a hadrosaur, the group of dinosaurs known as "duckbills."  At 22 feet long and over a ton, it was a medium sized hadrosaur, although big by modern standards.  Maiasaura was a plant eater, and living in herds may have been its best defense against the smaller relatives of Tyrannosaurus that lived in its time, such as Gorgosaurus.

Gastonia burgei is a medium sized armored dinosaur that lived in western North America during the Early Cretaceous, around 125-120 million years ago. A slow plant eater that weighed less than a ton, Gastonia relied on its armor to ward off predators.

Albertaceratops nesmoi
Albertaceratops was named in January of 2007.  This original skeleton is currently the only one on display in the world.  This specimen was found in Montana, near the Canadian border.  Albertaceratops lived across much of western North America during the Late Cretaceous, 75 million years ago.
Albertaceratops was named after Alberta, Canada.  A very good skull was found on private land in Canada.  Because the land owner was exceptionally helpful in the process of digging up the specimen, they named it after his home province (Alberta) and the second part, "nesmoi," is the landowners last name.

Triceratops horridus, Cretaceous, Wyoming
(Wyoming State Dinosaur)
Triceratops (three-horned face) was one of the largest and most spectacular dinosaurs of the group called Ceratopsians.  It reached a length of 30 feet and weighed up to 5 tons.  
Triceratops lived on the North American continent in the late Cretaceous period at the same time as Tyrannosaurus rex.  Its long horns and solid frill made it a formidable opponent of these large predators.  It is believed that horns and frill also fulfilled a social function.  Horn impressions in some frills indicate that Triceratops held head to head ramming contest, much like rhinos do today.
The first Triceratops was discovered in the 1880s in the Lance Creek Formation near Lance Creek in Niobrara County, Wyoming. Most of the specimens found at that time made their way to the museums in the eastern United States and Europe.
This specimen was unearthed in eastern Wyoming in 1991.  More than 80% of the specimen is original bone.

The Morrison Formation
The Morrison Formation is the name of the rock layer that we dig in here at the Wyoming Dinosaur Center.  All of the animals you see in front of you are found tin the Morrison Formation, and many have been dug up right here in Thermopolis.
Shown on this sign are just some of the many species of dinosaur that have been named from the Morrison Formation.  Many of the best known dinosaurs, such as Stegosaurus, Allosaurus, and of course Supersaurus lived when these Late Jurassic rocks were being deposited.  Just like today, however, not all animals live in the same environment. Some may have only been here during some times of the year, while others may have tracked changing rainfall patterns.  With additional research we hope to find out. 

Othnielia was actually a medium-sized dinosaur; although compared to other Morrison giants like Supersaurus and Allosaurus it certainly looks small.  Just like today, most animals in the Jurassic were not towering elephant-sized giants.  Most of the animals were smaller in size, including smaller dinosaurs, mammals, and primitive lizards.

Rosie is tired and just can't do the research anymore.
And she has a backlog of posts.
You're just going to have to read for yourself
and look at the pictures.

I'm always on the lookout for snakes,
but didn't see any.

No comments: