From Rockford Register Star : Discovery Center: Fossils aren't just bones to dinosaur detectives
The job of a detective is not so different from that of a
paleontologist. Just as detectives discover and then connect clues to
weave the story of what really happened, paleontologists puzzle over a
Cretaceous crime scene looking at more than just the “bare bones” to get
a sense of what life and death was like tens of millions of years ago.
“Fossils” are not just bones. And fossils may or may not have completely turned to rock. Fossils can be of shells or teeth or claws; imprints of leaves or skin or feathers; footprints; even petrified droppings.
And just as investigators are trained to spot otherwise invisible clues like a bit of thread or a single hair, dinosaur detectives know how to distinguish bumps on a rock from the three-fingered handprints left behind by a flock of pteranodons (tuh RAN uh dons) when examining a sandstone slab that was once a Jurassic beach.
Pteranodons were flying reptiles. Walking required that these creatures lean heavily on their wing joints. Their wings stretched along their arms and between their fingertips, similar to those of today’s bats. Unlike bats (that have only a thumb exposed), pteranodons had a thumb and two fingers protruding from the wing joint that took most of their weight when they walked.
What does a pteranodon handprint look like? Find out.
1. Dunk your hand in water.
2. Splay out your wet fingers and thumb so each is as far from the other as you can stretch it.
3. Use that stretched-out hand to lean on a paper towel or piece of newspaper, but touch it only with your thumb, index finger, and middle finger. Keep your ring finger and pinky in the air.
Does the handprint you made look sort of like a curvy letter “F”? So does the handprint of a pteranodon.
Sandstone slabs exposed on some of the islands in Glendo State Park in Wyoming contain pteranodon (and other dinosaur) prints. Our team uncovered, circled, and numbered some of them before making a latex cast of the site.
Unlike what you see on TV or in the movies, dinosaur bones at a dig site are A.) probably not all there, and B.) usually jumbled up instead of in perfect anatomical order (scientists use the word “disarticulated” to describe that jumbled heap of bones). Several things can contribute to disarticulation, including having the carcass of a dead dino eaten or scavenged prior to being covered by sediments. Any detective can tell you that evidence found at the crime scene does not necessarily all belong to the victim. The same is true for fossils at a dinosaur dig. How do paleontologists sort out a pile of bones and teeth to figure out who was eaten and who was eating? The teeth will tell.
To decipher Mesozoic mastication, think about how you lost your “baby teeth.” When a child loses a “baby tooth,” the tooth underneath it is already growing. The growth of that other tooth triggers the release of a chemical, which dissolves the roots of the baby tooth. Without its roots, the baby tooth is no longer attached to the jaw. The baby tooth becomes loose and wiggly and ready to fall out as the other tooth gets bigger and pushes the baby tooth up from below. Once a baby tooth falls out, the new tooth can grow in and take its place.
Modern-day sharks and crocodiles (like dinosaurs and unlike people), rely on sharp teeth for survival. They have many, many more than two sets of teeth. These predators shed their worn-down teeth as they chew. Fossil skulls of adult carnivorous dinosaurs such as T-rex reveal short barely-protruding teeth next to long sharp teeth — new sharp teeth growing in to replace shed teeth.
Shed dinosaur teeth are the spent “bullets” or “shell casings” that a paleo-detective examines. If a tooth is found that still has the root (and sometimes part of the bone) connected to it, that dinosaur was already dead when the tooth broke away. If a tooth is found with no root, a dinosaur shed that tooth while chewing.
Each species of meat-eating dinosaur has distinctive teeth. When Tyrannosaurus rex bones are uncovered, the shed teeth found nearby belong to dinosaurs like the tiny tyrannosaur found by the Burpee diggers. Paleo-detectives argue that little “Janes” gnawed away at the biggest meat-eater in the Cretaceous.
“Fossils” are not just bones. And fossils may or may not have completely turned to rock. Fossils can be of shells or teeth or claws; imprints of leaves or skin or feathers; footprints; even petrified droppings.
And just as investigators are trained to spot otherwise invisible clues like a bit of thread or a single hair, dinosaur detectives know how to distinguish bumps on a rock from the three-fingered handprints left behind by a flock of pteranodons (tuh RAN uh dons) when examining a sandstone slab that was once a Jurassic beach.
Pteranodons were flying reptiles. Walking required that these creatures lean heavily on their wing joints. Their wings stretched along their arms and between their fingertips, similar to those of today’s bats. Unlike bats (that have only a thumb exposed), pteranodons had a thumb and two fingers protruding from the wing joint that took most of their weight when they walked.
What does a pteranodon handprint look like? Find out.
1. Dunk your hand in water.
2. Splay out your wet fingers and thumb so each is as far from the other as you can stretch it.
3. Use that stretched-out hand to lean on a paper towel or piece of newspaper, but touch it only with your thumb, index finger, and middle finger. Keep your ring finger and pinky in the air.
Does the handprint you made look sort of like a curvy letter “F”? So does the handprint of a pteranodon.
Sandstone slabs exposed on some of the islands in Glendo State Park in Wyoming contain pteranodon (and other dinosaur) prints. Our team uncovered, circled, and numbered some of them before making a latex cast of the site.
Unlike what you see on TV or in the movies, dinosaur bones at a dig site are A.) probably not all there, and B.) usually jumbled up instead of in perfect anatomical order (scientists use the word “disarticulated” to describe that jumbled heap of bones). Several things can contribute to disarticulation, including having the carcass of a dead dino eaten or scavenged prior to being covered by sediments. Any detective can tell you that evidence found at the crime scene does not necessarily all belong to the victim. The same is true for fossils at a dinosaur dig. How do paleontologists sort out a pile of bones and teeth to figure out who was eaten and who was eating? The teeth will tell.
To decipher Mesozoic mastication, think about how you lost your “baby teeth.” When a child loses a “baby tooth,” the tooth underneath it is already growing. The growth of that other tooth triggers the release of a chemical, which dissolves the roots of the baby tooth. Without its roots, the baby tooth is no longer attached to the jaw. The baby tooth becomes loose and wiggly and ready to fall out as the other tooth gets bigger and pushes the baby tooth up from below. Once a baby tooth falls out, the new tooth can grow in and take its place.
Modern-day sharks and crocodiles (like dinosaurs and unlike people), rely on sharp teeth for survival. They have many, many more than two sets of teeth. These predators shed their worn-down teeth as they chew. Fossil skulls of adult carnivorous dinosaurs such as T-rex reveal short barely-protruding teeth next to long sharp teeth — new sharp teeth growing in to replace shed teeth.
Shed dinosaur teeth are the spent “bullets” or “shell casings” that a paleo-detective examines. If a tooth is found that still has the root (and sometimes part of the bone) connected to it, that dinosaur was already dead when the tooth broke away. If a tooth is found with no root, a dinosaur shed that tooth while chewing.
Each species of meat-eating dinosaur has distinctive teeth. When Tyrannosaurus rex bones are uncovered, the shed teeth found nearby belong to dinosaurs like the tiny tyrannosaur found by the Burpee diggers. Paleo-detectives argue that little “Janes” gnawed away at the biggest meat-eater in the Cretaceous.
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