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AndyS

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Reply with quote  #1 
This section comprises the jurassic Echinodermata,
i.e. the

Echinoidea / echinoids / sea urchins
Crinoidea   / crinoids   / sea lilies
Asteroidea / asteroids / starfish
Ophiuroidea / ophiuroids / brittle stars

of which macro fossils can be found.

The fossil Holothuroidea / sea cucumbers are only really known from microfossils.

While in some strata more or less complete echinoids are quite common, complete (articulated) crinoids, asteroids and ophiuroids are quite rare. Stem segments of crinoids on the other hand are quite common and are often overlooked.



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AndyS

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Crinoid

Eocomatula interbrachiatus (BLAKE, 1876)

01012008170508.jpg 
Incomplete crown of crinoid 

Size : 3" / 8 cm diameter
Location : Robin Hoods Bay
Age : Lower-middle lias, davoei-margaritatus zone

Diagnostics : This crinoid has an extremely short stem, usually only the crown is found.


References : 
SIMMS : British Lower Jurassic Crinoids, Palaeontographical Society, London, December 1989




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AndyS

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Crinoid

Seirocrinus subangularis (MILLER, 1821)

01012008172950.jpg 
Stem piece of crinoid,approx. 1.5"/ 3 cm in length 

01012008172915.jpg 
Stem segment of crinoid,4 mm diameter 

Location : Hawsker
Age : Lower-upper lias, pictured specimen probably from tenuicostatum subzone

Diagnostics : Stems can get quite long, usually only isolated segments found, stems up to 1 cm thick. 


References : 
SIMMS : British Lower Jurassic Crinoids, Palaeontographical Society, London, December 1989




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AndyS

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Crinoid

Hispidocrinus scalaris (GOLDFUSS, 1831)

01012008174809.jpg 
Stem piece of crinoid with attached cirri,approx. 1.5"/ 3 cm in length 

01012008174734.jpg 
Stem segments of crinoid,5 mm diameter 

01012008174843.jpg 
Crown of crinoid with thorn, 3" / 8 cm diameter 

06072008131850.jpg 
Crown of crinoid with thorns from underside, 1"/2.5 cm diameter

Location : Robin Hoods Bay
Age : Lower lias

Diagnostics : Species is characterized by development of a multiple thorns on the calyx, possibly to deterr predators

References : 
SIMMS : British Lower Jurassic Crinoids, Palaeontographical Society, London, December 1989




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TqB

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Crinoid
 

Isocrinus robustus (WRIGHT, 1858)

 

IMG_1101_-_Copy_a.JPG 

Stem segment, 9mm diameter

 

Location: Saltburn, also recorded from Staithes.

 

Age: upper Sinemurian - Pliensbachian.

 

This species is uncommon on the Yorkshire coast, occurring in the figulinum Sub-zone within the Staithes Sandstone Formation.

 

References : 
SIMMS : British Lower Jurassic Crinoids, Palaeontographical Society, London, December 1989

 

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