1A Collections

TF0907 Regular echinoid

Fri, 21 Jun 2019 11:21:57 +0100

Title

TF0907

Regular echinoid

Description

Stratigraphic Range

Modern

Taxonomy

Phylum: Echinodermata
Class: Echinoidea
Subclass: Regularia

Distinctive Features

Pentaradial symmetry
Anus and peristome in line
Spine attachments
Ambulacra
Attachments for the jaw apparatus visible on the inside of the peristome

Preservation

Original shell material
Jaw apparatus disarticulated
Soft parts removed

Advanced notes

Look at the colour of the shell and compare it to the permineralised specimens. Colour is almost always lost in the fossilisation process, even when the preservation looks to be near-perfect.

TF0906 Regular echinoid (cast)

Fri, 21 Jun 2019 11:20:21 +0100

Title

TF0906

Regular echinoid (cast)

Description

Taxonomy

Phylum: Echinodermata
Class: Echinoidea
Subclass: Regularia

Distinctive Features

Pentaradial symmetry
Anus and peristome lie in line
Spine attachments
Five sets of ambulacra

Preservation

Cast (internal mould of an external mould)

Advanced notes

Spine attachments very much larger than for irregular echinoids as they have to hold much larger spines. Spines on regular echinoids are for defence and preventing predation, unlike for irregular echinoids where the spines are for movement in burrows. Watch a video of regular echinoids moving: BBC Wildlife Army of Sea Urchins

TF0905 Irregular echinoid

Fri, 21 Jun 2019 11:18:21 +0100

Title

TF0905

Irregular echinoid

Description

Stratigraphic Range

Upper Cretaceous

Taxonomy

Phylum: Echinodermata
Class: Echinodea
Subclass: Irregularia
Order: Holasteroida

Distinctive Features

Bilateral symmetry
Mouth and anus out of line
Five radial ambulacra
Interambulacra with plates

Preservation

Sediment infill
Mineral replacement of shell

Advanced notes

Set 1: Anus and mouth appear to have been drilled to emphasise their positions.
Set 2: Fracturing of shell around the anus which obscures it. This would be a weak part of the shell which diagenetic processes have crushed.

TF0904 Irregular echinoid

Fri, 21 Jun 2019 11:15:24 +0100

Title

TF0904

Irregular echinoid

Subject

Source

Quaternary River Gravel, derived from Cretaceous chalk

Description

Stratigraphic Range

Cretaceous

Taxonomy

Phylum: Echinodermata
Class: Echinoidea
Subclass: Irregularia
Order: Echinoneoida
Genus: Conulus

Distinctive Features

Bilateral symmetry
Five radial ambulacra
Interambulacra
Migrated periproct (opening for anus)
Peristome (opening for mouth)

Preservation

This fossil was collected in Quaternary river gravel. Originally it was preserved in the Upper Chalk (Cretaceous). This was broken up into clasts by erosive processes, one of which was this irregular echinoid. The echinoid clast was carried by a river downstream and deposited in the river gravel unit during the Quaternary.

Advanced notes

Note how the anus has migrated, but the peristome is still in the position you would expect from a regular echinoid (not migrated). Notice also how the ambulacra bearing the tube feet continue onto the underside, a feature not seen in more streamlined and derived irregular echinoids.

TF0903 Irregular echinoid

Fri, 21 Jun 2019 11:08:48 +0100

Title

TF0903

Irregular echinoid

Subject

Location

Upper Chalk, Weston Colville, Cambridgeshire

Description

Species

Praecursor

Stratigraphic Range

Cretaceous

Taxonomy

Phylum: Echinodermata
Class: Echinoidea
Subclass: Irregularia
Order: Spatangoida
Genus: Micraster

Distinctive Features

Bilateral symmetry
Five radial ambulacra
Peristome (opening for mouth) and periproct (opening for anus) migrated
Spine attachment scars

Preservation

Sediment infil
Shell mineral replacement
Disarticulation of spines

Advanced notes

Note the streamlined shape for burrowing through the sediment, and how the ambulacra, which bear the tube feet, do not continue onto the underside of the animal where the mouth is.
This is because the tube feet are used for respiration but not for movement, for which small spines are used.

TF0902 Irregular echinoid

Fri, 21 Jun 2019 11:06:07 +0100

Title

TF0902

Irregular echinoid

Subject

Location

Coralline Oolite, Upware, Cambridgeshire

Description

Species

depressus Lestre

Stratigraphic Range

Jurassic

Taxonomy

Phylum: Echinodermata
Class: Echinoidea
Subclass: Irregularia
Order: Holectypoida
Genus: Holectypus

Distinctive Features

Bilateral symmetry
Five radial ambulacra
Spine attachment scars (very small)
Peristome and anus out of line

Preservation

Shell mineral replacement
Sediment infil
Disarticulation of spines

Advanced notes

This is a primitive irregular echinoid which would have had a functional jaw apparatus (not preserved) held within the peristome. The anus has migrated and the symmetry is bilateral, so this echinoid is clearly identifiable as irregular.

TF0804 Apiocrinites

Fri, 21 Jun 2019 10:47:35 +0100

Title

TF0804

Apiocrinites

Subject

Location

Bradford Clay

Description

Stratigraphic Range

Jurassic

Taxonomy

Phylum: Echinodermata
Class: Crinoidea
Order: Millericrinida
Genus: Apiocrinites

Distinctive Features

Pentaradial symmetry
Calyx
Attachment point for 'arms' of the animal

Preservation

Cast (manmade)

Echinoid

Fri, 21 Jun 2019 09:12:57 +0100

Title

Echinoid

Description

Taxonomy

Phylum: Echinodermata

Class: Echinoidea

Diagnostic features

Ambulacra (tube feet)

Periproct (opening for anus)

Peristome (opening for mouth)

Pentaradial symmetry (regular echinoids)

Bilateral symmetry imposed upon pentaradial symmetry (irregular echinoids)

Stratigraphic range

Ordovician to Present (Irregular Echinoids from Jurassic to Present)

Way of life

Regular echinoids:

Grazers with functional jaw apparatus

Long spines for protection and movement

Epifaunal at a wide range of depths

Use tube feet for respiration and movement

Irregular echinoids:

Feed on organic matter in sediment, front shaped to funnel sediment into mouth

Use fine spines to move

Infaunal burrowers

Use tube feet for respiration

Advanced notes

Grazing echinoids leave a distinctive pentagonal feeding trace Gnathicnus pentax.

Learn about types of preservation

Specimens

Browse echinoids

Crinoid

Fri, 21 Jun 2019 09:06:13 +0100

Title

Crinoid

Description

Taxonomy

Phylum: Echinodermata

Class: Crinoidea

Diagnostic Features

Crown

Stalk

Pentaradial symmetry

Ossicles

Calyx

Pinnule

Holdfast

Way of life

Benthic (some pseudoplanktonic)

Filter feeders

Stratigraphic range

Ordovician to present

Advanced Notes

The heyday of the crinoids was the Palaeozoic, where they dominated shallow marine environments. Modern crinoids are exclusively deep marine, and the diversity of forms is far less than it was during the Paleozoic.

Were they victims of the increased grazing and predation pressure of the Mesozoic Marine Revolution?

Specimens

Browse crinoids

Links

youtube: modern crinoid behaving pseudoplanktonically. You can see the pinnules, crown and multiple stalks.

flickr: beautiful photographs of both living and fossil crinoids. Compare the levels of detail you can see, admire the colours, and spot the distinctive features that make these crinoids identifiable.

Learn about types of preservation

Coral

Thu, 20 Jun 2019 12:42:14 +0100

Title

Coral

Description

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