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Fossils may be found either associated with a geological formation or at a single geographic site. Geological formations consist of rock that was deposited during a specific period of time. They usually extend for large areas, and sometimes there are different important sites in which the same formation is exposed.
Fish fossils, commonly those of the ray-finned Semionotus, can be found in limestone layers within the formation. [1] In other layers, indeterminate fossil ornithischian tracks have been noted, [5] along with additional reptile and dinosaur prints. Fossil plant remains, as well as root structures and pollen, are also found in the formation. [1]
The earliest direct evidence of life are stromatolites found in 3.48 billion-year-old chert in the Dresser formation of the Pilbara Craton in Western Australia. [4] Several features in these fossils are difficult to explain with abiotic processes, for example, the thickening of laminae over flexure crests that is expected from more sunlight. [57]
Skeletal fragments: this type of limestone texture can be found as whole micro-fossils, whole large fossils or broken up fragments of larger fossils. This is the most common texture. The kinds of skeletal particles present depend upon the age of the rock and the paleoenvironmental conditions from the time they were deposited.
Spinosauridae (or spinosaurids) is a clade or family of tetanuran theropod dinosaurs comprising ten to seventeen known genera.Spinosaurid fossils have been recovered worldwide, including Africa, Europe, South America and Asia.
A derived, reworked or remanié fossil is a fossil found in rock that accumulated significantly later than when the fossilized animal or plant died. [100] Reworked fossils are created by erosion exhuming (freeing) fossils from the rock formation in which they were originally deposited and their redeposition in a younger sedimentary deposit.
Since they are globally distributed – described on all continents except Antarctica – geographical boundaries do not appear to be a factor; [156] the same fossils are found at all palaeolatitudes (the latitude where the fossil was created, accounting for continental drift - an application of paleomagnetism) and in separate sedimentary ...
A troodontid theropod who is known from fossil teeth. Fossils have also been found in the Lance Formation in Wyoming. Pectinodon [96] [95] P. bakkeri [96] [95] Montana; UCM 38445, a fossilized tooth. Teeth of this genus have been found too. A troodontid theropod who is known from fossil teeth. Fossils have also been found in the Lance Formation ...