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1972 — Niles Eldredge and Stephen Jay Gould propose punctuated equilibrium, claiming that the evolutionary history of most species involves long intervals of stasis between relatively short periods of rapid change. 1974 — Donald Johanson and Tom Gray discover a 3.5 million-year-old female hominid fossil that is 40% complete and name it "Lucy."
Index fossils must have a short vertical range, wide geographic distribution and rapid evolutionary trends. Another term, "zone fossil", is used when the fossil has all the characters stated above except wide geographical distribution; thus, they correlate the surrounding rock to a biozone rather than a specific time period.
One archosaur group, the dinosaurs, were the dominant land vertebrates for the rest of the Mesozoic, [109] and birds evolved from one group of dinosaurs. [105] During this time mammals' ancestors survived only as small, mainly nocturnal insectivores, which may have accelerated the development of mammalian traits such as endothermy and hair. [110]
Skeletal mount of the Tyrannosaurus holotype.. This timeline of tyrannosaur research is a chronological listing of events in the history of paleontology focused on the tyrannosaurs, a group of predatory theropod dinosaurs that began as small, long-armed bird-like creatures with elaborate cranial ornamentation but achieved apex predator status during the Late Cretaceous as their arms shrank and ...
The history of paleontology traces the history of the effort to understand the history of life on Earth by studying the fossil record left behind by living organisms. Since it is concerned with understanding living organisms of the past, paleontology can be considered to be a field of biology, but its historical development has been closely tied to geology and the effort to understand the ...
Unearthed in a rock layer dating back to the Triassic period, between 252 million and 201 million years ago, the Gondwanax paraisensis fossil comes from the time when dinosaurs as well as mammals ...
Harold Urey argued that comet impacts may have caused mass extinctions in the past and may have been responsible for demarcating the periods of the geologic time scale. [27] 1974. Jan Smit began studying the extinction of foraminifera at the K–T boundary in Caravaca, Spain. He observed that some of these extinctions must have been rapid. [28 ...
c. 201.4 ± 0.2 Ma – Triassic-Jurassic extinction event marks the end of Triassic and beginning of Jurassic Period. The largest dinosaurs, such as Diplodocus and Brachiosaurus evolve during this time, as do the carnosaurs; large, bipedal predatory dinosaurs such as Allosaurus. First specialized pterosaurs and sauropods. Ornithischians diversify.