(from Greek: παλαιό (palaio)
, "old, ancient"; όν (on)
, "being"; and logos
, "speech, thought") is the study of prehistoric
life forms on Earth through the examination of fossils
This includes the study of body fossils
, tracks (ichnites
, cast-off parts, fossilised faeces
and chemical residues.
Modern paleontology sets ancient life in its context by studying how long-term physical changes of global geography paleogeography and climate paleoclimate have affected the evolution of life, how ecosystems have responded to these changes and have adapted the planetary environment in turn and how these mutual responses have affected today's patterns of biodiversity. Hence, paleontology overlaps with geology (the study of rocks and rock formations) as well as with botany, biology, zoology and ecology – fields concerned with life forms and how they interact.
The major subdivisions of paleontology include paleozoology (animals), paleobotany (plants) and micropaleontology (microfossils). Paleozoologists may specialise in invertebrate paleontology, which deals with animals without backbones or in vertebrate paleontology, dealing with fossils of animals with backbones, including fossil hominids (paleoanthropology). Micropaleontologists study microscopic fossils, including organic-walled microfossils whose study is called palynology.
There are many developing specialties such as paleobiology, paleoecology, ichnology (the study of tracks and burrows) and taphonomy (the study of what happens to organisms after they expire). Major areas of study include the correlation of rock strata with their geologic ages and the study of evolution of lifeforms.
(meaning 'parrot lizard') was a genus
of psittacosaurid ceratopsian dinosaur
from the Early Cretaceous Period
of what is now Asia
, about 130 to 100 million years ago
. It is notable for being the most species
-rich dinosaur genus; At least eight extinct
species are recognized from fossils
found in different regions of China
, with possible additional species from Thailand
All species of Psittacosaurus were gazelle-sized bipedal herbivores characterized by a high, powerful beak on the upper jaw. At least one species had long, quill-like structures on its tail and lower back, possibly serving a display function. Psittacosaurs were extremely early ceratopsians and, while they developed many novel adaptations of their own, they also shared many anatomical features with later ceratopsians, such as Protoceratops and the elephant-sized Triceratops.
Psittacosaurus is not as familiar to the general public as its distant relative Triceratops but it is one of the most completely known dinosaur genera. Fossils of over 150 individuals have been collected so far, including many near-complete skeletons. Most different age classes are represented, from nestling through to adult, which has allowed several detailed studies of Psittacosaurus growth rates and reproductive biology. The abundance of this dinosaur in the fossil record has led to its use as an index fossil for Early Cretaceous sediments of central Asia. (see more...)