User:Abyssal/Prehistory of North America

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The Prehistory of North America Portal

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Fossil of Opabinia regalis from the Burgess shale on display at the Smithsonian in Washington, DC..

Opabinia is an extinct stem-arthropod genus found in Cambrian fossil deposits. The only known species, O. regalis, is known from the Middle Cambrian Burgess Shale Lagerstätte of British Columbia, Canada. Fewer than twenty good specimens have been described. Opabinia was a soft-bodied animal of modest size, and its segmented body had lobes along the sides and a fan-shaped tail. The head shows unusual features: five eyes, a mouth under the head and facing backwards, and a proboscis that probably passed food to the mouth. Opabinia probably lived on the seafloor, using the proboscis to seek out small, soft food.

When the first thorough examination of Opabinia in 1975 revealed its unusual features, it was thought to be unrelated to any known phylum, although possibly related to a hypothetical ancestor of arthropods and of annelid worms. However other finds, most notably Anomalocaris, suggested that it belonged to a group of animals that were closely related to the ancestors of arthropods and of which the living animals onychophorans and tardigrades may also be members.(see more...)

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Petrified Forest National Park is a United States national park in Navajo and Apache counties in northeastern Arizona. Named for its large deposits of petrified wood, the park covers about 146 square miles (380 km²), encompassing semi-desert shrub steppe as well as highly eroded and colorful badlands. The site, the northern part of which extends into the Painted Desert, was declared a national monument in 1906 and a national park in 1962.

The Petrified Forest is known for its fossils, especially fallen trees that lived in the Late Triassic, about 225 million years ago. The sediments containing the fossil logs are part of the widespread and colorful Chinle Formation, from which the Painted Desert gets its name. Beginning about 60 million years ago, the Colorado Plateau, of which the park is part, was pushed upward by tectonic forces and exposed to increased erosion. All of the park's rock layers above the Chinle, except geologically recent ones found in parts of the park, have been removed by wind and water. In addition to petrified logs, fossils found in the park have included Late Triassic ferns, cycads, ginkgoes, and many other plants as well as fauna including giant reptiles called phytosaurs, large amphibians, and early dinosaurs. Paleontologists have been unearthing and studying the park's fossils since the early 20th century. (see more...)

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Did you know?

...that an effigy mound in the shape of a turtle is located in the Beattie Park Mound Group in downtown Rockford, Illinois?
... that the fossil mantidfly Dicromantispa moronei was first described from a single specimen in a private collection?
... that Native Americans lived at the Canfield Island Site (pictured) on the West Branch Susquehanna River in Pennsylvania for thousands of years, and now hold an annual pow wow there?
... that the extinct Miocene age maple Acer smileyi has been classified as closely related to the living Acer nipponicum (pictured)?
... that Mound 72 (pictured) at Cahokia in pre-Columbian western Illinois was the site of ritual human sacrifice, including a pit burial containing 53 young women?

... that the Stonerose fossil site contains the earliest known records of Rosaceae, the rose family?
... that the extinct Syndesus ambericus is the only stag beetle known from the Caribbean?
... that Archaeomarasmius, Aureofungus, Coprinites, and Protomycena are the only four genera of agaric mushrooms known from the fossil record?
... that unlike the living golden-club Orontium aquaticum (pictured), the extinct species Orontium mackii may not have needed wetlands to grow?
... that the scorpionfly family Eorpidae has a single genus, Eorpa, described in 2013?

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Rock formations known as the Tepees in Petrified Forest National Park Arizona, USA. The exposed rock layers belong to the Blue Mesa Member of the Chinle Formation and are about 220 to 225 million years old. The colorful bands of mudstone and sandstone were laid down during the Triassic, when the area was part of a huge tropical floodplain.
Photo credit: User:Finetooth