What are fossils ?

Devil’s toenail

An iconic fossil for an icon of palaeontology. Mary Anning (1799-1847), now one of the most celebrated pioneers ofpalaeontology, is usually associated with her famous discoveries of marine reptiles such as Ichthyosaurs andPlesiosaurus and the pterosaur Dimorphodon. Gryphaea obliquata, along with Gryphaea arcuata, are commonlyreferred to as Devil’s toenails and are both found in the Lower Lias (Lower Jurassic) of Britain. They may not be themost obvious choice to associate with Mary, but as one of the most distinctive and abundant fossils of the LowerLias, Gryphaea was as familiar to her as it is to fossil collectors that scour the beaches at Lyme Regis today

Arthropods in amber

Some of the earliest fossils of pre-historic arthropods - dating to about 230 million years ago - have been discovered entombed inamber. Arthropods - a highly diverse family of invertebrates, which includes insects, arachnids and crustacea - constitute morethan 90% of the entire species within the animal kingdom.

Amber is fossilised plant resin. The resin often entraps plant and animal material which then become buried - as "inclusions" -when the fossil amber forms.

A key feature of amber is its ability to preserve key features - such as the soft body parts - of the inclusions. It has become animportant aid to understanding the early evolution of life.

Stromotolites – the oldest fossils?

Stromatolites are rock-like build-ups of microbial mats that form in limestone- or dolostone-forming environments. They typicallyform by the baffling, trapping, and precipitation of particles by communities of microorganisms such as bacteria and algae. Insome cases, they can form inorganically, for example when seawaters are oversaturated with certains chemicals resulting inprecipitation. Stromatolite-building communities include the oldest known fossils, dating back some 3.5 billion years when theenvironments of Earth were too hostile to support life as we know it today.

Branches of fossil study

Paleobotany = plant kingdom Paleozoology = animal kingdom Human paleontology = pre-history Micropaleontology = plant and animal fossil micro-organisms

Paleobotany = plant kingdom Paleozoology = animal kingdom Human paleontology = pre-history Micropaleontology = plant and animal fossil micro-organisms

Decay

Aerobic decay – with oxygen = rapid Anaerobic decay – without oxygen = slower Aerobic decay – with oxygen = rapid Anaerobic decay – without oxygen = slower

Moulds and casts

CrystalsThe fossilized shellcavitiesare filled with crystals

Trace fossilsDinosaur tracks Starfish

Slug tracksSlug tracks