GLOSSARY

INTRODUCTION

This page is a list of technical terms used on the other pages on this site. Feel free to browse through the glossary, or just click on the links any time there is a term you don't understand, or would like to know more about.

ARCHOSAUR
A group, including the pterosaurs, dinosaurs, birds and crocodiles that formed the dominant vertebrate family from the Late Triassic until the K-T boundary.
BIOSTRATIGRAPHY
Biostratigraphy is a part of palaeontology that deals with using fossils to work out how two units of rock ('strata') relate in space and time.
CAMBRIAN
The Cambrian is a geological period that began about 570 Ma ago and ended 505Ma ago. During this period many marine animal groups radiated quickly. Named after the Roman name for an ancient Welsh tribe.
CONVERGENT EVOLUTION
The tendancy of organisms to develop superficially similar structures, usually to solve the problems of living in the same sort of environment. For example, birds and bats both have wings, but do not have the same skeletal structure to their wings because of their different ancestors.
CRETACEOUS
The final geological period of the Mesozoic. It lasted from 140 Ma until 65 Ma ago. This is the period that saw the dinosaurs (except the birds!), pterosaurs and the ammonites die out. Named after the Latin (Creata) for chalk, due to the large chalk deposits laid down in Western Europe during this period.
DEVONIAN
A geological period that extended from 395 Ma ago to 345 ma ago. Named after the county of Devon in England.
DIAPSIDS
A special name for a group of animals that have two holes, called fenestra, in their skull behind their eye socket. This allowed their jaws to become more powerful by changing the way the muscles were attached.
DIVERSE
This means the same as diversity or biodiversity. It is measure of how many different species exist in an area at a given time. There are various ways to calculate diversity, and the best way to measure it is a cause of arguements amongst scientists still.
ECOLOGY
The study of how organisms interact with each other and their physical environment. To do this ecologists look at ecosystems.
ECOSYSTEM
All the members of a biological community and the physical environment the community exists in. Nutrients move around ecosystems in loops. For example: plants get energy and nutrients from the sun and soil are eaten by herbivores and carnivores eat the herbivores. Material is then returned to the soil by animal waste and bacteria that decompose carcasses.
JURASSIC
One of the geological periods that makes up the Mesozoic era. It lasted from 190 Ma until 140 Ma. Named after the Jura mountains on the Swiss-French border.
K-T BOUNDARY/EVENT
The mass extinction that occured at the boundary between the Cretaceous(K) and the Tertiary(T) is known as the K-T event. This is famous because it marks the end of the 160 Ma reign of the dinosaurs and related archosaurs. There is strong evidence that a bolide impacted on the Earth just off the coast of Mexico at this time, but there is growing evidence that this acted as the final straw to the dinosaurs, which had been gradually declining anyway. For more click here.
LIVING FOSSILS
An organism that has no living relatives, although its fossil relatives are well known. This does not mean that it has not changed since its ancestors evolved, but it will have changed very little.
MASS EXTINCTION
An event in which large numbers of species die out in a very short time across the whole of the Earth. The K-T event was one of the 'Big Five', the five largest mass extinctions.
MESOZOIC
This term literally means 'middle life'. This is based on the old division of geological time into three eras, the Palaeozoic, Mesozoic and Cenozoic or Cainzoic. This era is made up of three periods. The Triassic, Jurassic and Cretaceous. In terms of millions of years this period lasted from 248 million years to 65 million years (Ma). For more on the Mesozoic click here.
MOLLUSCS
A group of invertebrates with soft bodies that occur in marine and freshwater and on land. They breath using gills and many species have protective shells.
NICHE
The way that an organism fits into an ecosystem, defined by what it eats, what eats it and other factors. Species cannot coexist without competition if they try to occupy the same niche.
PERMIAN
The geological period that lasted from 280 Ma ago to 225 Ma ago. At the end of this period the largest mass extiction ever to hit life on Earth occured. Up to 96% of all species died out. The period is named for the province of Perm in Russia.
PHOTOSYNTHESIS
A chemical process that allows plants to make organic molecules from carbon dioxide and water, using the energy of the sun. Nearly all forms of life are either direct consumers of plants or eat the flesh of herbivores, so without photosynthesis there would e little or no life on Earth. Photosynthesis also supplies nearly all the oxygen in the atmosphere, another vital role of plants.
PRECAMBRIAN
The part of the geological record that exists before 570 Ma. As the Earth is about 4.6 BILLION years old it is a very long period of time!
PRIMARY PRODUCER
A producer is an organism that acts as a food source for the next level up in the 'food chain'. Green plants are primary producers, because they are the lowest link in the food chain.
RADIATION/ADAPTIVE RADIATION
These terms refer to events during which a single species gives rise to many other species. The flowering plants are a good example of this, as are the dinosaurs. These events often happen after mass extinction events, but not always.
SOLNHOFEN LIMESTONE
A famous Jursassic deposit located in Bavaria in Germany. Many well preserved fossils have been found in this area, including fish, pterasours, turtles and the famous Archeopteryx. Such deposits are known as Lagerstatten. This is a German word meaning 'bonanza'.
TRIASSIC
The first geological period of the Mesozoic. It lasted from 225 Ma until 190 Ma. This period saw many land animal groups come and go, ending with the archosaurs diversifying into many of the niches available.
THEOCODONT
A group of animals with their teeth set in sockets.