Moab Happenings Archive
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PALEO HAPPENINGS April 2021

Triassic Troops, Troubadours and Tridactyls by Martin Lockley, Moab Giants

The Late Triassic bipedal dinosaur Coelophysis is the New Mexico State Fossil: seen here chasing lunch: artwork by Mark Hallet in the author’s collection.
Paleontologists know the Triassic as the “age of archosaurs” or ancient reptiles. As the first period in the age or Era of Dinosaurs, it was named for its three part (“tri”) division of rock types in Europe, in 1834, in the same year 25-year-old Abraham Lincoln was first elected to the Illinois state legislature. The Triassic Period lasted most exactly 50 million years from 250-200 million years ago and followed the largest extinction the biosphere had ever experienced. Nevertheless, surviving reptiles did well, including the first dinosaurs that appear at the end of the period
The Chinle Formation is famous for Petrified Forest National Park, where giant logs remain where they one fell. Fossil wood is the Arizona state fossil. Polished sections make prized gemstones
Triassic 220-210 million years ago. These earliest forms were mostly small bipedal animals the size of a turkey or perhaps an Emu, with three-toed, bird-like ‘tridactyl’ or trident shaped feet. The most famous example from the western USA is Coelophysis (“see-LOW-fi-sis”) which has been adopted as the New Mexico state fossil. Thousands of its remains were found at a famous site, appropriately named Ghost Ranch. This paleontological mecca was a favorite retreat of Georgia O’Keefe and has been preserved as an educational center and National Natural Landmark.

As the Late Triassic pterodactyl once flew, Ghost Ranch is not far from the Four Corners area and some of the most famous of all Triassic landscapes, including Petrified Forest National Park. The town of Chinle, in Apache County, Arizona sits amid the colorful rocks of the Chinle Formation which make up the Painted Desert badlands. Arizona has adopted its’ beautiful fossil wood as the state fossil. The Chinle fauna tells us of a ‘lost world’ of faunal diversity. Many new anatomical designs trooped onto the Late
In this Late Triassic scene a giant croc-like phytosaur gapes as small bipedal dinosaurs run by. Artwork by Doug Henderson in the author’s collection.
Triassic stage. Giant salamander like amphibians (metoposaurs) reached lengths of 10 feet ( 3 m), but these were dwarfed by crocodile-like phystosaurs that reached lengths of 20 feet (6 m). Both fed on abundant fish. The swamps would not have been a safe place for paddling or swimming. Relatives of the plants we know as today’s horsetails grew to more than 15 feet (5m). Descendants of mammal-like reptiles that had flourished before the extinction included a 3 m-long ox- sized, tusked form called Placerias. For good measure we can add an armored form, also a good 3 m-long, that looked much like the true armored dinosaurs of later periods. There were many more anatomical experiments, not least of which was an aquatic reptile named that looked like a miniature marine pleisiosaur (or for conspiracy theorists -the fabled Loch Ness Monster). The first true mammals where tiny and inconspicuous.

Perhaps it is poetic license to refer to these “troops” of weird and wonderful animals, as troubadours. The image of a Triassic menagerie has been used before, but surely the ancient world was not silent. Besides dressing up in weird and wonderful anatomical garb, to emulate dinosaurs, oxen, crocodiles, miniature Loch Ness monsters or mice, these creatures presumably grunted, snorted, squeaked and squealed their way through life. Paleo-artists and museum exhibitors have recreated many Late Triassic scenes enriched by a diversity of plant and animal restorations. These life forms may mostly be gone or transformed into descendants which appeared with roles in life’s later chapters. But, use your little imagination if you go to the Painted Desert, or look at the colorful grey-green and reddish- purple shales that make up the slopes below the steep, orange, Wingate Sandstone cliffs west of Moab and west of Highway 191, especially just west of Moab Giants, you may in your mind’s eye be transported to a lost world, lush, green, tropical, swampy and teeming with life.
Four weird and wonderful Triassic animals all look to be emulating animals from other time periods. Clockwise from top left, a mammal like form, a giant amphibian, and armored archosaur and a small plesiosaur-shaped aquatic reptile.

 
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