TF0703

Atrypa

Specimen Age

TF0704

Chonetes

TF0705

Spirifer verneuli

Specimen Age

TF0706

Ornithella

TF0707

Terebratula biplicata

TF0708

Terebratula maximes

TF0753

Leptaena

Coral

Taxonomy

Phylum: Cnidaria

Class: Anthozoa

Diagnostic features

Radial or biradial symmetry

External skeleton

Septa

Tabulae

Stratigraphic range

Ordovician to present

Tabulate, rugose: Ordovician to Permian (extinct at P/T extinction)

Scleractinian: Triassic to present

Way of life

Colonial or solitary

Filter feeding

Reef builders

Advanced notes

Remember, although the most well-known modern corals enjoy a symbiotic relationship with photosynthesising algae (Zooxanthellea) many modern corals do not. When thinking about Palaeozoic corals do not assume that they lived as well known corals do now.

Corals built their skeletons out of aragonite (Ordovician to Permian) or calcite (Triassic to recent). They are often preserved as moulds, casts, intact or replaced.

Specimens

Browse corals

External links

Paleosoc coral info

Nautiloid

Taxonomy

Phylum: Mollusca

Class: Cephalopoda

Diagnostic features

Simple suture

Chambers

Central siphuncle

Straight, curved or coiled shell

Stratigraphic range

Cambrian to recent

Straight forms: Cambrian to Permian

Coiled forms: Devonian to Present

Way of life

Predatory

Buoyancy controlled by changing gas/liquid contents of chambers

Marine

Preservation

Commonly preserved as internal moulds

Modern nautiloids preserved with original shell material

Learn about types of preservation

Advanced notes

Nautiloids originated in the Cambrian period, and radiated during the Ordovician. These early nautiloids had conical shaped shells. In the Silurian some nautiloids used curved shells, and by the Devonian some were coiled. The evolution of the coiled shell from the straight is thought to be driven, at least in part, by increased mobility of a coiled shell compared to a long straight one.

Nautiloids could be confused with ammonoids. You can distinguish them by the location of the siphuncle and the complexity of the suture pattern. Nautiloids, unlike ammonoids, are not extinct, although only six species remain today (compared to thousands in the Palaeozoic). This means that if presented with modern shell material it is likely a nautiloid and not an ammonoid.

Specimens

Browse nautiloids

External links

Telling planispiral fossils apart

Graptolite

Taxonomy

Phylum: Hemichordata

Class: Graptolithina

Diagnostic features

Stick-shape (often branched)

One or both edges may appear serrated

Thecae

Rhabdosome

Stipes

Stratigraphic range

Cambrian to Carboniferous (Dendroids)

Ordovician to Middle Devonian (Graptoloids)

Way of life

Colonial

Planktonic (mostly, although some dendroids were sessile benthonic)

Suspension feeders

Typical preservation

Flattened along bedding planes, normally in shales

Carbonization or pyritization of the animal

Learn about types of preservation

Advanced notes

Graptolites, because of their abundance and variation in morphology are very good index fossils. At a very basic level the angle between the stipes and number of stipes can be used to give a rough age for the fossil, with Early Ordovician graptolites having two stipes with the 'sawtooth' facing each other (pendent), later Ordovician graptolites having a more open oblique or reflex angle between the 'sawtooth' faces, and Siluran graptolites having the 'sawtooth' faces back to back (scandent) or having lost one stipe altogether (for example monograptids).

Specimens

Browse graptolites