|You might also like:||Painted Flowerpot Craft||Mardi Gras: Spelling Word Questions||W: Early Reader Books||Drawing and Coloring Worksheets: Winter K-3 Theme Page||Farm Animals Beginning Readers Books||Today's featured page: Plant Glossary|
New evidence strengthens the link between dinosaurs and birds
August 12, 2000
Ornithomimids, or "ostrich mimics," were bird-like dinosaurs. These fast runners had long, slender legs, a long neck, a stiff, tapered tail, short arms, a small head, large eyes, and a toothless, beaked mouth. Ornithomimids lived during the late Jurassic period until the late Cretaceous period. These omnivores probably ate small animals (like insects and small reptiles) and plants. Ornithomimus, pictured above, was an ornithomimid dinosaur.
Dr. John M. Rensberger, a vertebrate paleontologist (specializing in mammals) from the University of Washington, USA, and Dr. Mahito Watabe, a paleontologist from the Hayashibata Museum of Natural Science, Japan, carefully examined the bones and teeth of many modern-day and extinct animals, studying how they varied as a function of the animals' habitat and food sources (published in Nature, August 10, 2000).
Microscopic structures like canaliculi (tiny passages in bone which connect blood vessels to cells) and collagen fibers (which strengthen bone) were painstakingly observed in thin sections of bones. It was found that birds and ornithomimid dinosaurs share similar arrangement of canaliculi, but those in mammals and plant-eating dinosaurs (like Triceratops and duck-billed dinosaurs) were quite different (the canaliculi were jumbled in birds and dinosaurs, but were radially arranged in mammals). A similar result was found for collagen; mammals and plant-eating dinosaurs had collagen fibers that were more systematically arranged than those of birds and ornithomimid dinosaurs.
Rensberger is planning on further, related investigations, including adding crocodiles to the study.
A page on birds and dinosaurs
A page on duck-billed dinosaurs, plant-eaters also called hadrosaurs.
A page on Triceratops, a three-horned plant-eating dinosaur.
All about birds.
A page on Archaeopteryx, the earliest-known bird
All about mammals
A Chart of geological time.
Over 35,000 Web Pages
Sample Pages for Prospective Subscribers, or click below
Overview of Site|
Enchanted Learning Home
Monthly Activity Calendar
Books to Print
Parts of Speech
The Test of Time
TapQuiz Maps - free iPhone Geography Game
Biology Label Printouts
Physical Sciences: K-12
Art and Artists
Label Me! Printouts
|Search the Enchanted Learning website for:|