Tuesday, June 7, 2016

Dinosaurs survive!

Is this how you view dinosaurs?...

Dinosaur flash cards from about 1968
Dinosaurs as depicted in my 1968 "Prehistoric Animals" flash card set.
That's how they were thought to look in the 1960's--slow, cold-blooded, lizard-like. Brontosaurus had to stay in deep water to support its massive bulk. Tyrannosaurus Rex had to lay out on the ground all morning to soak up enough warm sun rays to finally move and seek carrion--its long tails dragging behind on the ground as it plodded along.

I think I got interested in dinosaurs about 1966 or so, after a visit to the Denver Museum of Nature & Science. I remember the Stegosaurus skeleton as it appears in the 1950's post card ("before" picture) in this post on Denver's Fighting Dinosaurs. In 1995 the Stegosaurus skeleton was remounted to appear more lifelike and interacts, now, with a new Allosaurus skeleton.

In the 1970's and 80's came the revolutionary idea of "hot-blooded dinosaurs." Now dinosaurs were depicted as active and more mammal-like (see the Jurassic Park movies). The dinosaurs were often posed more horizontally than in the past, their necks stretching forward and tails lifted off the ground. Apatosaurus (the former Brontosaurus) now ran around in herds on dry land. And T-Rex could run and chase, not just look for already dead animals to scavenge.

But that's not how dinosaurs are viewed today. Recent fossil discoveries reveal that many dinosaurs sported feathers. I received a recent blog post from the Cornell Lab of Ornithology, a part of Cornell University devoted to the study of birds. The post was about dinosaurs: "They Had Feathers: Is the World Ready to See Dinosaurs as They Really Were?". Included in the article were depictions of colorful and fully-feathered herds of active dinosaurs running through patches of snow--quite the change in habits, physiology, and habitat than previously thought! I suggest you click on that link and check it out. Most scientists today view birds as direct descendants of theropod (carnivorous bipedal; think T-Rex and Velociraptor) dinosaurs. In 2012 Matthew P. Martyniuk even wrote A Field Guide to Mesozoic Birds and Other Winged Dinosaurs.

This change in hierarchical classification makes for quite the confusion. Birds are still considered to be the biological order of Aves, equal in taxonomic rank to the order of mammals and the order of reptiles. However, reptiles now contain dinosaurs. Dinosaurs are divided into several groups including theropods. Birds are a subdivision of theropods. Birds are now a way-down-the-line group of reptiles, yet co-equal. Confused? Good. I didn't want to be the only one.

Birds are the only dinosaurs to have survived the Cretaceous-Paleogene extinction event, when 75% of plants and animals perished. All non-avian dinosaurs perished when a meteor or asteroid crashed into the Gulf of Mexico 66 million years ago. At least, that's the present theory, feathers and all.

How do you view dinosaurs now?...

Domestic Pigeon Dinosaur
Domestic Pigeon Dinosaur