field museum – Dinosaur Lady

Parasaurolophus

Dinosaurs left behind skeletons, eggs, footprints, even fossilized poop. All these things help us imagine what the world of the dinosaurs looked like. But we really don’t have much of an idea what it sounded like. We can be pretty sure that the dinosaurs’ world echoed with the thud of gigantic feet, the splash of water, and the buzz of insects. But did dinosaurs bark, howl, grunt or growl? We don’t know.

Leandra Walters, Phil Senter, James H. Robins, CC BY 2.5, via Wikimedia Commons

However, scientists do think that one dinosaur “played a horn.” That dinosaur was Parasaurolophus (par-uh-sore-oh-loaf-us). Scientists have made models of the long, hollow crest on its head, and when they blew air through it, it made a deep, low tone, like a musical instrument.

This link https://www.youtube.com/watch?v=QtpSOpUDCb8 will help showcase what Parasaurolophus might have sounded like.

The crest of Parasaurolophus was a very long, thin tube of bone. It began at the dinosaur’s nose and stretched up way above its head. On some Parasaurolophus the crest reached six feet long – longer than most people! This crest was hollow inside. A tube for air went up from each nostril to the tip of the crest and then curved back down like a trombone. All the air it breathed had to make that long journey. Not even Pinocchio had a nose that long!

In every other way Parasaurolophus was ordinary. It was one of the plant eaters nicknamed “duckbilled” because its mouth was long and flat like a duck’s bill. It stood on two strong back legs, with shorter front legs that it could also walk on or use as arms. It was about 30 feet long and 16 feet tall, and it probably weighed 3 or 4 tons. This was about the size of a bus – or an average dinosaur.

Size comparison of person and *Parasaurolophus* *walkeri*

Parasaurolophus might have used the sounds it could make with its crest to communicate different messages, such as danger or food ahead. A herd might have honked at a Tyrannosaurus to go away. A special kind of honk might have attracted a mate.

Parasaurolophus also might have used its crest to push away branches in a thick forest. The cassowary, a large flightless Australian bird, uses its crest for that today. Another idea is that the crest brought cool air close to the Parasaurolophus’ brain to keep it from getting too hot. And it might have been able to smell through it, so it could seek out its favorite plants or tell when a meat eater was close by.

Scientists don’t know for sure if the Parasaurolophus used its crest in any of these ways. They continue to look for clues and ideas.

Marco Antonio Pineda, CC BY-SA 4.0, via Wikimedia Commons

Scientists do know that Parasaurolophus had strong jaws which would be good for eating tough plants, such as pine needles, leaves, and different fruits and seeds. Its cheeks were loaded with good teeth for grinding things up. It even had three or four extra teeth above the ones that showed. That way if any of its teeth broke or wore out, new ones moved down. A Parasaurolophus may have grown more than 10,000 teeth during its lifetime.

Parasaurolophus lived right up to the end of the age of dinosaurs, outliving the other known duckbilled dinosaurs. But sixty-six million years ago, the last dinosaurs on earth died, including Parasaurolophus. Never again will the world echo with the sound of those gigantic feet or the honk of a Parasaurolophus calling to its friends.

Sources (Click Me!)

Norman, David. The Illustrated Encyclopedia of Dinosaurs. Crescent Books, 1985.

“Parasaurolophus.” Natural History Museum of London. https://www.nhm.ac.uk/discover/dino-directory/parasaurolophus.html

“The Real Parasaurolophus.” Philip J. Currie Dinosaur Museum. 2024. https://dinomuseum.ca/2021/01/the-real-parasaurolophus

Riehecky, Janet. Parasaurolophus. The Child’s World, 1990.

Baryonyx: The Fishing Dinosaur

When the dinosaurs lived, they often had just one thing on their minds – FOOD! Whether a dinosaur ate plants or meat, getting food was a full-time job. Scientists have found evidence that at least one type of dinosaur went fishing for its food. That dinosaur was Baryonyx (BAR-ee-ON-ix).

Ballista, CC BY-SA 3.0, via Wikimedia Commons

Scientists know Baryonyx was a meat eater because it had the sharp curved teeth needed to cut through meat. But in many ways, it was different from other meat-eating dinosaurs.

Most meat-eating dinosaurs had strong jaws, heavy skulls, and enormous teeth, so they could slice through tough skin and bone. But Baryonyx’s jaws were not very strong, and its head was long and flat, like a crocodile’s. Its teeth were much smaller than most meat eaters’ – and it had almost twice as many of them. Baryonyx was not made for attacking other dinosaurs. It was made for catching fish.

A lot of animals like the taste of fish, but it takes a very special kind of animal to catch them. Fish dart about very quickly in the water. To catch them, an animal has to be even quicker. Fish are also very slippery. Holding onto them takes special claws or teeth.

So, how could Baryonyx catch fish? Scientists have suggested several ways. It might have stood by the edge of a shallow lake, waiting as patiently as a heron. When an unsuspecting fish swam by, it might have snapped it up. Its long mouth and many sharp teeth could have grabbed a quick-moving fish and held onto it no matter how much it wiggled.

Or the Baryonyx might have played crocodile. Some scientists picture it floating in the water, watching carefully. If a fish swam by, it was scooped up in the long mouth of Baryonyx.

Another way it might have fished was with its front feet. It could use its front feet as hands. It had long, slender fingers which may have been used to grab fish. Or if it didn’t feel like grabbing, it might have gone “spear fishing.” The name Baryonyx means “heavy claw.” It got this name because it had a huge claw, one of the biggest dinosaur claws that has ever been found – 12 inches long! Scientists think Baryonyx had one of the super claws on each front foot. It could stand in shallow water, waiting. Then, when a fish swam past, it could stab quickly into the water and catch it.

What makes scientists so sure Baryonyx ate fish? The first skeleton found had fish scales where its stomach would have been. They also found a few bones of a plant-eating dinosaur. How did Baryonyx hunt large plant eaters when it wasn’t a very big or strong dinosaur? Well, many scientists think it let a powerful meat eater like Megalosaurus do all the work. Megalosaurus might kill a plant eater too big for it to eat. Baryonyx could come by when it was done and eat the leftovers. So, the life of Baryonyx was like a vacation – lots of fishing and somebody else prepares the food!

PaleoGeekSquared, CC BY-SA 4.0, via Wikimedia Commons

Scientists don’t know much about how Baryonyx lived. They don’t know if it traveled in a pack or alone, they don’t know if it took care of its babies or left them on their own, and they don’t know if it had feathers or scaly skin. They can describe its size because the first skeleton found of it was 85% complete. It grew about 30-33 feet long and was about twice as tall as an average person. Its legs were short compared to some dinosaurs and lacked strong muscles, so it wasn’t a runner. It was not very strong in general, but its large claw would have made a great weapon to defend itself. Only a very big and very hungry meat eater would have bothered it.

Scientists are fascinated by this dinosaur because it’s so different from other dinosaurs. The wide variety of dinosaurs makes them very interesting to study, and each new discovery adds to our picture of what they were like.

Sources (Click me!)

“Baryonyx.” Natural History Museum, London. https://www.nhm.ac.uk/discover/dino-directory/baryonyx.html

Paul, Gregory S. The Princeton Field Guide to Dinosaurs. Princeton University Press, 2010. pp. 87-88.

Riehecky, Janet. Baryonyx. The Child’s World, 1990.

Ankylosaurus: The Walking Tank

Most of the dinosaurs that lived millions of years ago were peaceful plant eaters. But, every now and then, into this peaceful life came meat eaters!

If a plant eater didn’t want to become dinner, it had to be able to defend itself. Some plant eaters were very good at this. They had sharp claws or horns of their own. But one type of dinosaur didn’t need to fight back. All it had to do was squat down. This was the Ankylosaurus (an-KI-luh-sawr-us). The Ankylosaurus had thick, bony armor over almost all of its body.

The Ankylosaurus was a huge dinosaur. That alone would have been enough to discourage most meat eaters. It was just a little smaller than a bus – about 26 feet long and 7 feet tall, weighing as much as five tons. But it didn’t look like a bus – it looked like a tank.

Tanks are covered with metal armor. The Ankylosaurus’ armor was made from thick bands or plates of bone. Spikes and knobs were scattered across the back and over the head. The armor covered its back, neck, and head – even its eyelids!

*Ankylosaurus* head cast
Tim Evanson, CC BY-SA 2.0, via Wikimedia Commons

The armor was probably very frustrating to a hungry meat eater. Even if a meat eater could dodge the knobs and spikes, all it would get was a mouthful of bony armor – and maybe a few broken teeth.

A meat eater had only one chance. The belly of the Ankylosaurus didn’t have any armor. If the meat eater could get to that soft spot, it could still have an Ankylosaurus snack. But all the Ankylosaurus had to do was crouch to the ground, folding its legs underneath. That way the only parts a meat eater could get to were covered with armor.

Some meat eaters probably tried to flip it on it back. If it were flipped over, the weight of its armor would prevent it from flipping back, much like a turtle. It would be completely helpless. However, trying to flip an Ankylosaurus was like trying to flip a tank. Most ankylosaurs were much too heavy for even the strongest meat eater to budge. And, of course, it was hard to find a place to grab on, with all those spikes and knobs in the way.

If a meat eater kept on bothering an Ankylosaurus, it ran the risk of provoking the creature into an attack. At the end of its tail, the Ankylosaurus had a huge, bony club. The club was about 16 inches wide and made of solid bone. The muscles in the tail were very strong. If an Ankylosaurus swung its club hard enough, it could probably have knocked down any other dinosaur, even a Tyrannosaurus. It might have been able to break a meat eater’s leg – or its skull – with that club. It certainly would have made that meat eater very sorry it ever wanted an Ankylosaurus for dinner!

Ankylosaurus had some trouble finding its own dinner. It was hard for it to move its head and neck because of all that armor. And it certainly couldn’t rear up on its back legs with all that heavy bone to lift. That meant that it could only feed on plants that grew close to the ground. Maybe that wasn’t all bad, though. Every now and then it might scoop up some ants or a few beetles for a tasty dessert.

You might think that the Ankylosaurus with its heavy armor was a slow-moving dinosaur, but it was more like a rhinoceros than a turtle. A rhinoceros is very large and heavy, but it can run fast. Ankylosaurus wasn’t as fast as a rhino, but it could run as fast as 6 mph, which is about as fast as most people can run. The powerful leg muscles of Ankylosaurus helped it to move quickly if it needed to.

Ankylosaurus was the biggest armored dinosaur that we know, but it was not the only one. It had many relatives. Some had more spikes. Some had few or none at all. Some had tail clubs. Some did not.

*Hylaeosaurus*
UnexpectedDinoLesson, CC BY-SA 4.0, via Wikimedia Commons

Yuxisaurus
Xi Yao, Paul M Barrett, Lei Yang, Xing Xu, Shundong Bi, CC BY 4.0, via Wikimedia Commons

But most of them were good at surviving. Many of the armored dinosaurs lived until the very end of the age of dinosaurs. It wasn’t easy living in the same world as Tyrannosaurus, but it could be done – by a walking tank!

Sources (Click Me!)

“Ankylosaurus.” Natural History Museum of London. n.d. https://www.nhm.ac.uk/ discover/dino-directory/ankylosaurus.html

“Cretaceous Insects.” Western Australian Museum. n.d. https://museum.wa.gov.au/ explore/dinosaur-discovery/cretaceous-insects

Norman, David. The Illustrated Encyclopedia of Dinosaurs. Crescent Books, 1985.

Rasmussen, Patty and Talon Homer. “Ankylosaurus: A Tank-like Herbivore With a Killer Club Tail.” How Stuff Works. 10 July 2024. https://animals.howstuffworks.com/ dinosaurs/ankylosaurus.htm?utm_source=facebook&utm_medium=social&utm_campaign=hsw-owned&utm_content=animals&fbclid=IwY2xjawFYdItleHRuA2Flb QIxMQABHSJZrzMY8s_ckpGF7a0h_hX_66x-bgLwyX_Zqb-4gJSO4DdqauNWL6RUmA_aem_vUroiI23KZyLQ6TE2xysxw

Riehecky, Janet. Ankylosaurus. The Child’s World, 1991.

Death of the Dinosaurs, Part 2

What is the evidence that an asteroid hit the Earth? The history of the Earth is recorded in rocks…

One of the most basic things geologists study are layers of rock. You’ve probably seen them.

Rock layers are easily seen in the Grand Canyon

These layers are laid down by sand, river silt, lava, and other inorganic ground cover. Some are formed quickly; others take thousands of years. Earthquakes can shove some layers up and others down. Each layer represents an era of time.

Scientists can determine the age of layers of rock by looking at fossils and elements found in the rock. Some elements are especially helpful in this because they change over time. For example, some forms of potassium change into argon. Scientists know how long it takes for this to happen (millions of years), so by measuring how much of a sample is still potassium and how much argon, they can tell how old the rock is. They can also do this with some uranium, which changes into lead. It’s more complicated than that, but that’s the basic idea.

Scientists have known for a long time that there is a layer of rock that marks the end of the dinosaurs. It’s called the K-Pg boundary and it dates to 66 million years ago, (K stands for the German word for Cretaceous and the Pg for Paleogene, the next time period.) Below that layer dinosaur fossils are found. No dinosaur fossils have ever been found above it.

At first, scientists believed that this extinction happened gradually. Dinosaurs died out because they were replaced by “superior” mammals. But in the mid-1970s, while studying layers of rock in Italy, geologists Walter Alvarez and Bill Lowrie, noted that the layer of rock below the K-Pg boundary had loads of microfossils of sea creatures in it, but a thin layer of clay just above it had almost none. It looked like nearly all these creatures had died suddenly. Alvarez realized that their near extinction occurred at the same time with a much bigger extinction – the dinosaurs!

Cretaceous-Tertiary boundary clay
Jeffrey Beall, CC BY 4.0, via Wikimedia Commons

Alvarez talked to his father, Luis Alvarez, a Nobel prize winning physicist, about the problem. His father had the idea of trying to look for the element iridium in order to tell if the layer of clay was deposited quickly (which could mean a catastrophe killed the dinosaurs) or gradually (which would mean scientists were right about dinosaurs dying off slowly). Iridium comes from asteroids. It’s very, very rarely found on Earth. But dust from asteroids drifts down through the atmosphere in tiny amounts at a consistent rate. If there was a lot of iridium dust, that would mean the extinction happened gradually. If a small amount, then it happened quickly.

But father and son were not prepared for what they found: a lot of iridium. That should have meant that the layer was laid down gradually, but it was too much iridium, nine times more than just dust could account for. They decided to look in another location of the K-Pg boundary to see if they found the same thing. They found a site in Denmark. It also had lots of iridium. Later a site in Spain got the same result.

Father and son discussed the idea that the iridium could have come from an asteroid hitting the Earth, but they couldn’t figure out how one impact could cause worldwide extinction. Walter presented the iridium data at a conference and met with lots of resistance. Scientists did not want to let go of the idea that dinosaurs had died out gradually.

Artist impression of asteroid impact
Donald E. Davis, Public domain, via Wikimedia Commons

Luis then had the idea that a large enough impact would cast so much debris into the air that sunlight would be blocked. With no sunlight, plants wouldn’t grow. Plant eaters would have nothing to eat and would die. Then meat eaters would have nothing to eat. This could cause mass extinction. Meanwhile, reports came in from all over the world showing lots of iridium in the K-Pg boundary. But nearly all scientists still rejected the idea of an asteroid impact leading to mass extinction.

Over the next decade other evidence of an impact was found in rocks. Scientists found shocked quartz in the K-Pg boundary. Shocked quartz is formed from a powerful shock wave (like an earthquake) passing through rock and deforming the structure inside regular quartz. An asteroid impact would have sent a shock wave like that through the ground. They also found tektites, which are made when rock is heated so hot it becomes liquid (usually by a volcano). Bits of liquid rock are flung into the air. When they get high enough, the rock solidifies, and it falls to Earth in a distinctive tear-drop shape. An asteroid hitting the Earth would have made an explosion so hot it would have melted the rock and produced tektites. Scientists also found sand deposits that indicated a tsunami had occurred and soot from the worldwide firestorm there would have been.

Tektite
James St. John, CC BY 2.0, via Wikimedia Commons

All this was great, but skeptics still held out. They asked, “If an asteroid hit the Earth, where is the crater that it would have formed?” It wasn’t until 1990 that scientists found that the Gulf of Mexico had been hiding the crater. The Chicxulub Crater in the Yucatan Peninsula became the smoking gun that confirmed that a huge asteroid had indeed struck the Earth. Scientists were able to date the crater to about 66 million years ago – the end of the Cretaceous Period and the end of the dinosaurs. This finally convinced most scientists.

The Formation of Chicxulub Crater
The original uploader was David Fuchs at English Wikipedia., CC BY 3.0, via Wikimedia Commons

Further research has strengthened the asteroid theory. The Chicxulub Crater is the largest impact crater on Earth, about 120 miles wide and 18 miles deep. The asteroid that hit it was about six miles wide and moving about 45,000 mph. As I said in my last blog, it hit with so much power that it blew a huge hole in the Earth and melted thousands of cubic miles of rock, throwing massive debris into the air. We now know that the rock bed of the impact site was limestone and anhydrite. These rocks would have released vast amounts of carbon dioxide, carbon monoxide, and sulfur into the air when they exploded. The sulfur would have combined with water to form acid rain. All this would have contributed to the extinction event by contaminating the air and reducing oxygen.

Imagine the horror of that day – an explosion 10 billion times bigger than the WWII atomic bomb, a tsunami with one-thousand-foot-high waves of water covering what is now Mexico and the southern United States, a magnitude 10 earthquake, a worldwide firestorm, and billions of tons of debris, ash, and acid rain polluting the atmosphere. And don’t forget, as I mentioned last week, there were huge volcanoes erupting in what is now India. We don’t know if the asteroid had anything to do with those eruptions or not, but they certainly contributed to the extinction event. About 75% of life on Earth became extinct.

It’s hard to picture it all, but a recent discovery in North Dakota gives us a freezeframe of that day. That site will be the subject of next week’s blog.

Death of the Dinosaurs: Part 1

Death of the Dinosaurs: Part 3

Sources (Click Me!)

Alvarez, Walter. T.rex and the Crater of Doom. Princeton University Press. 1997.

“Asteroid as Powerful as 10 Billion WWII Atomic Bombs May Have Wiped Out the Dinosaurs.” CNN. 10 September 2019. https://wtop.com/gallery/science/asteroid-as-powerful-as-10-billion-wwii-atomic-bombs-may-have-wiped-out-the-dinosaurs/

“Asteroid Impact that Killed Dinosaurs Triggered ‘Mega-Earthquake’ that Lasted Months.” Press Release Montclair State University. 19 October 2022. https://www.montclair.edu/newscenter/2022/10/19/asteroid-impact-killed-dinosaurs-triggered-mega-earthquake-lasted-months/

Black, Riley. “What Happened in the Seconds, Hours, Weeks After the Dino-Killing Asteroid Hit Earth?” Smithsonian Magazine. 9 August 2016. https://www.smithsonianmag.com/science-nature/what-happened-seconds-hours-weeks-after-dino-killing-asteroid-hit-earth-180960032/

Cornell, Sean, et al. “The Tsunami that Killed Dinosaurs!” InTeGrate. Pennsylvania State. n.d. https://www.e-education.psu.edu/earth107/node/1623

Kaufman, Mark. “Scientists Reveal Deadly Earth just after the Dinosaur Asteroid Hit.” 4 November 2023. Mashable. https://mashable.com/article/dinosaur-extinction-asteroid-cause

Lea, Robert. An Asteroid and Volcano ‘Double Punch’ Doomed the Dinosaurs, Study Suggests. Space.com. 21 Sept. 2022. https://www.space.com/dinosaur-extinction-volcanoes-aided-asteroid-impact

Osterloff, Emily. “How an Asteroid Ended the Age of the Dinosaurs.” Natural History Museum of London. n.d. https://www.nhm.ac.uk/discover/how-an-asteroid-caused-extinction-of-dinosaurs.html

Roden, Nathan. “How Did We Find Out that an Asteroid Killed the Dinosaurs?” ScIU Indiana University Bloomington. 8 April 2023. https://blogs.iu.edu/sciu/2023/04/08/an-asteroid-killed-the-dinosaurs/

Smith, Roff. “Here’s What Happened the Day the Dinosaurs Died.” National Geographic. 111 June 2016. https://www.nationalgeographic.com/animals/article/what-happened-day-dinosaurs-died-chicxulub-drilling-asteroid-science

The Day the Dinosaurs Died, Part 1

Everyone knows an asteroid killed the dinosaurs. But is that all we know? Join me as we go down the rabbit hole of how the dinosaurs went extinct…

Sixty-six million years ago, life on Earth was very different from today. Trees, ferns, and flowering plants covered the land. There wasn’t any grass (despite what the picture below shows. I couldn’t find a free Cretaceous scene anywhere without green ground). Grass hadn’t evolved yet.

User:Debivort, CC BY-SA 3.0, via Wikimedia Commons

The only mammals were small creatures, no bigger than about three feet long. Dinosaurs dominated the planet. There were small dinosaurs, medium-sized dinosaurs and BIG dinosaurs. They lived in every part of the world. They lived in valleys and on mountains. They lived in dry places and wet places. They lived in forests and on open plains. They had ruled the Earth for 180 million years, and it seemed they would continue to do so indefinitely.

But out in space an asteroid was plunging toward Earth. It was about six miles wide and the height of Mt. Everest. When it reached the Earth’s atmosphere, it would have looked like a fireball brighter than the sun. It was seen, though, for only a few seconds before it hit the Earth because it was hurtling through the air at about 45,000 mph! It hit in the Yucatan Peninsula in Mexico, forming a crater that covers a large portion of the Gulf of Mexico. The crater has been named Chicxulub (CHICKS-ih-lube) Crater.

NASA/JPL-Caltech, modified b, Public domain, via Wikimedia Commons

The asteroid hit with a force 10 billion times larger than the atomic bomb detonated on Hiroshima, blowing a hole in the ground 120 miles wide and 18 miles deep. Imagine how loud that explosion must have been! In an instant, the intense heat of the explosion vaporized the asteroid and turned thousands of cubic miles of rock into liquid and spewed it into the air, like a colossal volcano erupting. Anything within 600 miles or more would have been instantly incinerated by the fireball. A combination of soot, sulfuric gases, and extremely fine dust was flung into the atmosphere. For the next several hours, titanic winds blew this debris around the whole Earth. They ignited a world-wide firestorm that probably killed most of life on Earth. In addition, a mega-earthquake shook all of Mexico and Central America, the southern United States, and as far south as far as Argentina. The earthquake (magnitude 13 – likely the biggest earthquake the Earth has ever felt) triggered giant tsunamis and mudslides. One-thousand-foot-high waves of water hit the coast where now Texas, Alabama, Mississippi, northern Mexico, and Cuba lie. Secondary waves traveled as far as what is now North Dakota.

Continent placement at the end of the Cretaceous Era
Merikanto, CC BY-SA 4.0, via Wikimedia Commons

Life that somehow survived this, now faced another horror. Dust and soot lingered in the atmosphere blocking most of the sunlight for at least a year. Without sunlight plants couldn’t grow and thrive. Plant eaters lost their food source and died. Meat eaters lost their food source and died. In addition, the lack of sunlight lowered the temperature on Earth by about 80° Fahrenheit.

As if this weren’t bad enough, volcanos in India had been erupting at this same time, with lava flows covering 190,000 square miles of land, killing all life in that area. The eruptions also added more toxic fumes and debris to the atmosphere.

Scientists disagree about how long it took, but about 75% of all life on earth, plant and animal, died because of the asteroid hit and the volcanos, including all the dinosaurs (except birds which most scientists believe are direct descendants of dinosaurs). Some small animals survived, including the ancestors of today’s frogs, snakes, lizards, alligators, crocodiles, a variety of insects, birds, and mammals.

How do we know all this happened? I’ll explain in my next blog.

Death of the Dinosaurs: Part 2

Death of the Dinosaurs: Part 3

Sources (Click Me!)

Black, Riley. “What Happened in the Seconds, Hours, Weeks After the Dino-Killing Asteroid Hit Earth?” Smithsonian Magazine. 9 August 2016. https://www.smithsonianmag.com/science-nature/what-happened-seconds-hours-weeks-after-dino-killing-asteroid-hit-earth-180960032/

Cornell, Sean, et al. “The Tsunami that Killed Dinosaurs!” InTeGrate. Pennsylvania State. n.d. https://www.e-education.psu.edu/earth107/node/1623

Kaufman, Mark. “Scientists Reveal Deadly Earth just after the Dinosaur Asteroid Hit.” 4 November 2023. Mashable. https://mashable.com/article/dinosaur-extinction-asteroid-cause

Lea, Robert. An Asteroid and Volcano ‘Double Punch’ Doomed the Dinosaurs, Study Suggests. Space.com. 21 Sept. 2022. https://www.space.com/dinosaur-extinction-volcanoes-aided-asteroid-impact

Osterloff, Emily. “How an Asteroid Ended the Age of the Dinosaurs.” Natural History Museum of London. n.d. https://www.nhm.ac.uk/discover/how-an-asteroid-caused-extinction-of-dinosaurs.html

Stegosaurus

Stegosaurus is one of the most iconic herbivores, but is also one of the most peculiar…

Many dinosaurs are strange. But one of the strangest is Stegosaurus. Imagine what you would look like if you walked on your feet and your elbows! Well, that’s sort of what Stegosaurus looked like. Its back legs were twice as long as its front legs. That meant its hips were stuck way up in the air – 9-13 feet! Its head and shoulders were close to the ground, and its back curved like a slide down to its tail. From front to back it was about 24-30 feet long, and it weighed about 5 ½ tons. In a bowling alley, it would take just two stegosaurs to stretch from the beginning of the alley all the way down to the bowling pins.

Stegosaurus skeleton at the Field Museum of Natural History in Chicago

That was certainly a strange shape, but Stegosaurus had an even stranger mouth. The front of its mouth was a beak, like that of a parrot or turtle. Most plant eaters have strong teeth that can grind up food, but not Stegosaurus. In the back of its mouth, it had rows of small, weak teeth. Its jaws could only move up and down, not to the side, which made chewing hard. As you can imagine, all this made it hard for Stegosaurus to eat. It could break off a mouthful of plants, but it couldn’t really chew them up very well before swallowing them. So, most things went down whole. There’s no evidence to indicate that it ate rocks (called gastroliths) as did other dinosaurs that couldn’t chew. The rocks helped break up the food in a special sac called a gizzard. But Stegosaurus didn’t do this. So, scientists have no idea how this strange creature managed to digest its food.

Frederick Berger, Public domain, via Wikimedia Commons

Stegosaurus not only had trouble eating – it also had trouble thinking. The Stegosaurus had a tiny head and probably the smallest brain compared to its size of any dinosaur. It was only about as big as a golf ball or walnut.

Stegosaurus might not have been very smart, but it knew enough to avoid somebody who tried to take a bite out of it. And there were plenty of creatures that wanted to take a bite out of Stegosaurus.

FabSubeject, CC BY-SA 3.0, via Wikimedia Commons

The Stegosaurus lived at the same time as the fierce Allosaurus and many other meat eaters. It couldn’t run fast, and it couldn’t think fast. It had to have some way to protect itself – so it grew a very strange weapon. Most dinosaurs that needed to defend themselves grew sharp claws on their feet or horns on their heads. But Stegosaurus did things backwards. It grew four, foot-long spikes on the end of its tail!

Fred Wierum, CC BY-SA 4.0, via Wikimedia Commons

These spikes were good weapons and helped the Stegosaurus, but they were not good enough to fight off a determined attack. So, Stegosaurus’ best chance for survival was either to hide from meat eaters (and it was too big to do that!) or to stay with a herd of stegosaurs. Like any bully, an Allosaurus would rather attack a Stegosaurus found alone than one with a lot of friends nearby.

Probably the weirdest thing about Stegosaurus was the plates on its back. Scientists have wondered whether there was one row of plates or two, whether they stood up straight or lay down flat, and whether they were arranged in pairs or alternated. They have also wondered what the plates were for.

They weren’t dinner plates – but they may have helped keep Stegosaurus from becoming someone else’s dinner, serving as defense. This isn’t too likely because their whole sides had no covering. Just protecting the top wasn’t very effective.

Or the plates may have worked to keep the Stegosaurus from becoming too hot. Their position and shape seem designed to pull heat from the body of Stegosaurus and let the wind carry it away. But dinosaur species similar to Stegosaurus, such as Kentrosaurus, have spikes instead of plates, which wouldn’t work as heat dispersers. Most likely, the plates may have been just for display, to help Stegosaurus attract a mate. Scientists have considered all of these ideas, but they have not been able to agree. They continue to study the plates, but they may never know for sure why Stegosaurus had them.

Kentrosaurus
Connor Ashbridge, CC BY-SA 4.0, via Wikimedia Commons

Scientists also don’t know much about the kind of life Stegosaurus led. Scientists have found Stegosaurus footprints which seem to indicate it traveled in herds, living on flat floodplains and in conifer forests bordering rivers. It is likely it ate plants that grew close to the ground, such as mosses or ferns. They think it laid eggs and that it probably left its babies on their own to take care of themselves because they weren’t smart enough to take care of them. Many reptiles, such as sea turtles and snakes, do this. But scientists don’t know for sure. There will always be things we don’t know about Stegosaurus. But that’s part of the fascination of this strange creature.

ABelov2014 (https://abelov2014.deviantart.com/), CC BY-SA 3.0, via Wikimedia Commons

Sources (Click Me!)

Naish, Darren. “The Stegosaurus Plate Controversy.” Scientific American. 11 July 2016. https://www.scientificamerican.com/blog/tetrapod-zoology/the-stegosaurus-plate-controversy/

Norman, David. The Illustrated Encyclopedia of Dinosaurs. Crescent Books, 1985.

Rafferty, John P. “Stegosaurus.” Britannica. 10 July 2024. https://www.britannica.com/animal/ ornithischian

Riehecky, Janet. Stegosaurus. The Child’s World, 1988.

Title Image from https://wallpaperaccess.com/stegosaurus

Uneasy Lies the Crown, Part 2

As I wrote a few weeks ago, there are some serious contenders for Tyrannosaurus’ crown as the biggest, fiercest land carnivore of all time. Giganotosaurus and Megaraptor could certainly give Tyrannosaurus a battle, but this week’s contenders, from Africa, are even more powerful.

Carcharodontosaurus (Kar-KAR-oh-don-toe-SAWR-us) lived in Northern Africa during the late Cretaceous Period 99 to 94 million years ago. Its name means “shark-toothed lizard,” and its long jagged-edged teeth are much like those of a shark.

https://upload.wikimedia.org/wikipedia/commons/f/f5/Carcharodontosaurus_Scale.svg

Most estimates rank Carcharodontosaurus as about three or four feet longer than Tyrannosaurus. It’s hard to tell because scientists have found only some tens of bones and a number of teeth from it.

Even if Carcharodontosaurus is slightly larger, Tyrannosaurus still has a number of advantages. Smithsonian Magazine reported that Tyrannosaurus’ bite force was almost 12,800 pounds, stronger than any other animal that ever walked on land. (Megalodon, an enormous extinct shark, does have it beat at 41,000 pounds. There was also an extinct crocodile named Purussaurus which had a bite of 15,500 pounds of force.) Tyrannosaurus’ bite was stronger than the force of an average-sized African elephant dropping on you. (I don’t want to even think what that means about Megalodon’s bite.) Tyrannosaurus’ teeth are shaped like bananas. The rounded shape is very effective at breaking bones. Carcharodontosaurus’ teeth were shaped differently. They were thinner, more like the blade of a knife. They were meant for shearing meat from bones. They might have broken if Carcharodontosaurus bit directly into thick bones.

Tyrannosaurus also had an advantage in eyesight. Its eyes were more forward looking than Carcharodontosaurus’. This gave Tyrannosaurus a wider range of sight, enabling it to see more of what was in front of it. Because of the shape of Carcharodontosaurus’ skull, it would have had to drop its head toward its chest to see any distance ahead. This likely meant it hunted its prey by ambushing them, rather than chasing after them. Regardless, if the two had ever met, it would have been a titanic battle.

Franko Fonseca from Redondo Beach, USA, CC BY-SA 2.0,via Wikimedia Commons

And then there’s the biggest of the top five, Spinosaurus. It also lived during the late Cretaceous Period and was found in North Africa. This creature was about 49 feet long and weighed just over eight tons. However, its back legs were much shorter than Tyrannosaurus’, making it about 9 feet tall at the hip compared to Tyrannosaurus’ 12-15 feet in height. However, if the sail on Spinosaurus’ back is included, then it was 15-16 feet tall.

Durbed, CC BY-SA 3.0, via Wikimedia Commons

It’s difficult to compare its power to the other three because it was shaped differently and lived a different kind of life. It was a little thinner, with a large sail on its back, a paddle-shaped tail and its jaws were long and narrow like a crocodiles’. Its teeth were like overturned ice cream cones instead of curved with jagged edges. Scientists think that it hunted at least part of the time in the water and that on land it stayed near the coast and ambushed its prey, rather than running it down. Its likely that, despite its huge size, its shorter legs would have made it less agile than Tyrannosaurus. Its tail would have been a formidable weapon for knocking other dinosaurs around, but that might not be enough.

Figure 1 (left) Spinosaurus tooth – 1 Jiří X. Doležal (about me), CC BY-SA 3.0, via via Wikimedia Commons. Figure 2 (right) Tyrannosaurus tooth

Scientists don’t know which of these dinosaurs was most powerful. Even though it’s been many years since Giganotosaurus, Megaraptor, Carcharodonotosaurus, and Spinosaurus were discovered, scientists still know very little about them. It takes a long time for fossil bones to be excavated and studied. For me, however, Tyrannosaurus still holds its crown by virtue of its long teeth, large brain, and powerful bite. But never forget that there is another alternative: any day a paleontologist might dig up a new dinosaur that could take on all of them.

What do you think?

Sources (Click Me!)

Aureliano Tito, Aline M. Ghilardi, Edson Guilherme, Jonas P. Souza-Filho, Mauro Cavalcanti, and Douglas Riff . “Morphometry, Bite-Force, and Paleobiology of the Late Miocene Caiman Purussaurus brasiliensis.” PLOS ONE. 17 Feb. 2015. https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0117944.

Black, Riley. “The Tyrannosaurus Rex’s Dangerous and Deadly Bite.” Smithsonian Magazine. Oct., 2012. https://www.smithsonianmag.com/science-nature/the-tyrannosaurus-rexs-dangerous-and-deadly-bite-37252918/

Currie, Philip J and Colleayn O. Mastin. The Newest and Coolest Dinosaurs. Grasshopper Books Publishing, 1998.

Gasparini, Zulma, Leonardo Salgado, and Rodolfo A. Coria (eds.). Patagonian Mesozoic Reptiles. Indianapolis: Indiana University Press, 2007.

Hecht, Jeff. “Contenders for the crown.” Earth 7.1 (Feb. 1998): 16. _Academic Search Premier_. EBSCO. Judson University Library, Elgin, IL.15 July 2009 <http://www.judsonu.edu:2048/login?url=htto://<http://www.judsonu.edu:2048/login?url=http://search.ebscohost.com/login.aspx?direct=true&db=aph&AN=89601&site=ehost-live>.

Horner, John R. and Don Lessem. The Complete T-rex. New York: Simon and Schuster, 1993.

Larson, Peter and Kenneth Carpenter. Tyrannosaurus Rex: The Tyrant King. Indianapolis: Indiana University Press, 2008.

Monastersky, R. “New beast usurps T. rex as king carnivore.” Science News 148.13 (23 Sep. 1995): 199. Academic Search Premier. EBSCO. Judson University Library, Elgin, IL. 15 July 2009 <http://www.judsonu.edu:2048/login?url=http://search.ebscohost.com/login.aspx?direct=true&db=aph&AN=9510094855&site=ehost-live>.

Novas, Fernando, E., Diego Pol Juan I. Canale; Juan D. Porfiri; Jorge O. Calvo. “A bizarre Cretaceous theropod dinosaur from patagonia and theevolution of Gondwanan deomaeosaurids. Proceedings: Biological Sciences, Mar2009, Vol. 276 Issue 1659, p1101-1107, 7p.

Rafferty, John P. “Megalodon.” Britannica. <https://www.britannica.com/animal/megalodon>.

Richardson, Hazel. Smithsonian Handbooks: Dinosaurs and Prehistoric Life. New York: Dorling Kindersley, 2003.

Sereno PC, Myhrvold N, Henderson DM, Fish FE, Vidal D, Baumgart SL, Keillor TM, Formoso KK, Conroy LL. “Spinosaurus is Not an Aquatic Dinosaur.” Elife. 2022 Nov 30;11:e80092. doi: 10.7554/eLife.80092. PMID: 36448670; PMCID: PMC9711522.

Smith, Nathan D., Peter J. Makovicky1, Federico L. Agnolin, Martin D. Ezcurra, Diego F. Pais3 and Steven W. Salisbury. “A Megaraptor -like theropod (Dinosauria: Tetanurae) in Australia: support for faunal exchange across eastern and western Gondwana in the Mid-Cretaceous.” Proceedings of the Royal Society. 20 May 2008.

“Spinosaurus.” Natural History Museum of London. nd. https://www.nhm.ac.uk/discover/dino-directory/spinosaurus.html

“Spinosaurus aegyptiacus.” The Sauropodomorph’s Lair. 23 Aug. 2020. <https://thesauropodomorphlair.wordpress.com/skeletal-reconstructions/dinosaurs/theropoda/spinosaurus-aegyptiacus/>

Spotts, Peter N. “Giant dinosaur fossil forces scientists to question theories.” Christian Science Monitor 03 Dec. 1997: 3. Academic Search Premier. EBSCO. Judson University Library, Elgin, IL. 15 July 2009. <http://www.judsonu.edu:2048/login? url=http://search.ebscohost.com/login.aspx?direct=true&db=aph&AN=9712050418&site=ehost-live>.

Stevens, Kent A. “Binocular vision in theropod dinosaurs.” Journal of Vertebrate Paleontology. 12 June 2006. 26 (2): 321–330. doi:10.1671/0272-4634. https://www.tandfonline.com/doi/abs/10.1671/0272-4634%282006%2926%5B321%3ABVITD%5D2.0.CO%3B2.

Straight, Will. “Carcharodontosaurus vs. Tyrannosaurus.” 2015. https://www.dinosaurhome.com/carcharodontosaurus-vs-tyrannosaurus-685.html

“Sue at the Field Museum.” The Field Museum, Chicago, IL. 2007. 15 July 2009.

University of Queensland. “Australian Dinosaur Found To Have South American Heritage.” ScienceDaily 15 June 2008. 10 September 2009 <http://www.sciencedaily.com /releases/2008/06/080613111410.htm>.

Dinosaur Trivia

I thought it would be fun to spice things up with some with a quiz!
Let me know your thoughts in the comments below.

The Discovery of Dinosaurs

Two hundred years ago, the word “dinosaur” didn’t exist. It didn’t need to. No one knew that giant reptiles had once walked the earth.

Occasionally people found large bones, but they usually thought they belonged to some animal, like an elephant or a giraffe. One piece of bone was thought to have been from a race of giant people. Dinosaur bones may even be responsible for the belief in dragons in ancient China. Then, in England, two gentlemen working separately discovered dinosaurs at about the same time.

The first was Dr. Gideon Mantell, a physician and amateur geologist. In 1822 his wife, Mary Ann Mantell, found some very large, unusual teeth in a pile of gravel. Mantell sent the teeth to other experts, but they dismissed them as belonging to a known animal. One paleontologist said they were from a rhinoceros. Mantell didn’t give up. He was sure the teeth were something special. He learned that the pile of gravel his wife had found the fossils in came from a nearby stone quarry. There he found more teeth and some bones. After much study, he determined that the bones and teeth came from a giant reptile. The teeth resembled those of the iguana lizard, but they were twenty times bigger!

Illustration of the original Iguanodon teeth found by Mantell
Gideon Mantell, Public domain, via Wikimedia Commons

In 1825, Mantell published a description of the creature, describing it as being at least 40 feet long. He named it Iguanodon (eh-GWA-nuh-don), Iguana from the iguana lizard and don, meaning tooth.

Meanwhile, in 1824, the Rev. William Buckland of Oxford came into the possession of some bones, including part of a jaw with teeth.

Mary Buckland, née Morland (1797-1857), Public domain, via Wikimedia Commons

These teeth were clearly those of a giant reptile. Buckland named it Megalosaurus (MEH·guh·luh·sore·us), which means “great lizard.” He published a description of it that same year, which means it was the first dinosaur described scientifically. Mantell was still struggling with skeptics, and, as I said above, he didn’t publish until 1825. But, in 1833, Mantell discovered another giant reptile, Hylaeosaurus (hy-LEE-oh-sore-us). Hylaeosaurus was an armored, plant-eating dinosaur that grew about 16 feet long. So he discovered two of the first three dinosaurs.

A scientist named Sir Richard Owen was the one who put it all together. He studied the bones and teeth of all three creatures. He found them to share some characteristics, such as fused vertebrae at the base of the spine. But he found them quite unlike modern reptiles. He determined that these three animals deserved their own category. In 1842, he invented the name dinosaurs, which means “terrible lizards,” to describe them.

People were excited about these huge creatures and wanted to know what they looked like. Scientists tried to figure out how to put together the bones that had been found. But it was like trying to put together a jigsaw puzzle with only half the pieces. They thought Iguanodon looked something like a fat rhinoceros. In 1852, a sculptor named Waterhouse Hawkins made life-sized models of what scientists thought Iguanodon and Megalosaurus looked like.

Statues of *Iguanadon* and *Megalodon* Jes from Melbourne, Australia, CC BY-SA 2.0, via Wikimedia Commons

He and the scientists made a lot of mistakes. For example, when they found a spike from the Iguanodon, they put it on its nose. It was really the creature’s thumb. But they didn’t know they’d made so many mistakes. In fact, they were anxious to show the world their dinosaurs. When the model was half done, they decided to have a dinner party – in the dinosaur!

Many important scientists were invited. The seating area was a bit crowded, but everyone had a wonderful time. This was probably the only time in history that a dinner was inside a dinosaur without being the dinosaur’s dinner!

Since that time, we’ve learned so much more about dinosaurs, including more about how Iguanodon and Megalosaurus looked. They stood with all four legs directly under their bodies and didn’t drag their tails. They were active, not slow, sluggish creatures. But the excitement people felt then is the same excitement people still feel today.

Sources (Click Me!)

Andrei, Mihai. “The Fearsome Megalosaurus: A Glimpse into the Jurassic World.” ZME Science. 9 August, 2023. https://www.zmescience.com/feature-post/natural-sciences/geology-and-paleontology/dinosaurs/megalosaurus/

Norman, David. The Illustrated Encyclopedia of Dinosaurs. Crescent Books, 1985.

Osterloff, Emily. “Dinosauria: How the ‘terrible lizards’ got their name.” London Natural History Museum. https://www.nhm.ac.uk/discover/how-dinosaurs-got-their-name.html

Walker, Bob. “Gideon Mantell: The Forgotten Man Who Discovered Dinosaurs.” The Guardian. 2020. https://www.theguardian.com/science/2019/feb/03/gideon-mantell-play-fight-over-first-dinosaur

Why You Should Visit a Fossil Lab

The best part of any museum is the dinosaurs– especially the huge skeletons! But they didn’t just walk into the museum on their own. And those bones weren’t always clean and perfectly shaped.

In fact, the bones fossil hunters dig up are usually damaged in some way. They might have been chewed on by predators or scattered about by wind or water. They can be cracked, split, or smashed. So how do they go from broken to beautiful? This happens in a fossil lab.

It starts with getting the bones safely back to the fossil lab. When a bone is dug out of the ground, sometimes it comes free easily. But more often the bone is attached to the rock, so fossil hunters need to carve out both. They use jackhammers and rock saws, pickaxes, hammers, and chisels.

Scientists call the rock next to the bone the matrix. Fossil hunters leave the matrix around the bone, so it can protect the bone. They cover the bone and its matrix with plaster to provide more protection. The whole thing can weigh several hundred pounds.

Small bones are packaged in crates while big bones may be lifted out by helicopter. They are all sent to a fossil lab. Unloading the bones must be done carefully. The big bones don’t always fit through the door. They need to come in through a loading dock.

Some bones are stored away. There are always more bones needing preparation than time and people to prepare them. Bones not being worked on are put on shelves or in specimen cabinets.

Other bones are brought into the prep lab to have the matrix removed from the bone. The workroom needs to have bright lights, so preparers can see what is rock and what is bone. It also needs good air flow because removing the matrix produces a lot of dust. Stations are set up around the room.

A work station needs to have a large, flat surface to place the fossil on. There should be storage space for the tools the preparer will need and its own light source. It may also have a microscope to study small fossils and an air tube to vacuum up the dust and tiny bits of rock. The preparer should wear protective goggles, a dust mask, and gloves. Preparers using noisy tools, such as a jackhammer, also need ear plugs.

When a bone is selected for preparation, first the preparers need to remove the plaster jacket. They use a cast-cutting saw, like the ones doctors use to remove a cast from a broken limb. A preparer might then use a small jackhammer called an air scribe to remove the matrix that is not too close to the bone.

When preparers get close to the bone, they need to be very careful. The bones break very easily. Using a small metal pick called a pin vise (pictured to the side), preparers scrape away the rock, just like when a dentist scrapes plaque from your teeth. They scrape in a direction away from the bone so that if they slip, they don’t hurt the bone. The key is to go slowly. Sometimes they use a magnifying glass to make sure they are scraping away only the matrix.

Bits of matrix are blown away with an air tube as they come off. Brushes can also be used to keep the surface clean, and a very sharp needle might be used to remove matrix in small cracks. Exposed bone is covered with glue to keep it from breaking apart.

Sometimes preparers use chemicals, such as acid, to dissolve the matrix, but they must be careful to make sure the chemicals don’t hurt the bone. It can take anywhere from a few minutes to hundreds of hours to remove all the matrix. Sometimes part of the matrix is left to hold delicate bones together.

Once the matrix is removed, there is still work to be done. Often the bone is broken, so the pieces must be put together. That can be like putting a jigsaw puzzle together. Very small bones can be kept together with wax. Others need glue, and others need wire or steel bands.

Putting together all the bones of a skeleton takes lots of patience. Preparers make sketches and 3-D models. Bones need to be placed next to each other in the same way they were when the dinosaur was alive. A natural-looking pose must be chosen.

It is rare that fossil hunters find all the bones for one dinosaur. Preparers need to figure out which bones are missing. To complete the skeleton, preparers may use bones from several dinosaurs of the same species. Sometimes they can figure out what a bone should look like by the bones around it. Then preparers can sculpt a bone from plaster or plastics.

Many of the prepared bones are stored in cabinets or lockers. They each have a number that tells when and where the fossil was found. Scientists can find the fossil they need and study it.

Sometimes the scientists make a cast of a bone. First, they make a rubber mold from the real bone. Then they put plaster or resin into the mold. When it dries, it’s a perfect copy. Museums often display casts rather than the real bones. This prevents damage to the real bones and makes it easier for scientists to study the real bones. Casts are also used to make model dinosaurs. Artists create realistic-looking dinosaurs for the movies or special exhibits. However, technology is already making this process easier and faster by using 3-D printing. In the future plaster casts will be a thing of the past.

To prepare a skeleton for an exhibit, it’s important for preparers to make sure every bone is stable. Fossils are very heavy, so the framework holding them up needs to be able to hold the weight without hurting the fragile fossils.

The bones are held together with such things as glue, metal pegs, bolts, wire, and thick cables. The preparers try to keep these out of sight because they want the dinosaur to look as natural as possible.

It can take several years to mount a big dinosaur. But when it’s all done, thousands and thousands of people will gaze up at the dinosaur skeleton and catch their breath with awe.

Would you like to work in a fossil lab? Please tell me why or why not in the comments section.

I took all the photos