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Jurassic Jumper
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Reply with quote  #1 
Name: Terebratula maxima.

Location: Found on the foreshore at Ramsholt, Suffolk.

Range: Coralline Crag.

Diagnostics: Unfortunately, only the pedicle valve is shown here, but you can clearly see the distinctive reinforced foramen (pedicle opening), through which this terebratulid brachiopod would extend it's thread-like byssus to attach itself to, for example, a rock, another shell, or the seabed. The shell wall is reasonably thick in the immediate vicinity of the foramen, but thins out markedly towards the anterior end of the valve, where it is remarkably thin for a shell of this size. As a paired example, you would see that classic (loosely) U-shaped join along the shell margin between the two valves. As with many brachiopods and terebratulids, there is a size asymmetry between the two valves, and the missing brachial valve is somewhat smaller. 

Size: Up to at least 8.5cm long, possibly more.

Reference: British Caenozoic Fossils (NHM) plate 32, ISBN 1-898298-77-7.

08012009152905.jpg 

08012009160442.jpg 

08012009160529.jpg 

(NB. scale in cm)

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"We try not to use the word insane, we prefer the term mentally hilarious..."



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Reply with quote  #2 
Name: Spisula arcuata.

Location: Found in the slippages at Walton-on-the-Naze, Essex.

Range: Coralline Crag - Chillesford Beds.

Diagnostics: The shell wall is quite thin and fragile (for its size), and the only external ornamentation is a number of irregularly placed growth ridges. The internal muscle scars are quite distinctive, but alas not really visible on this specimen (see reference below).

Size: Max diameter up to at least 6.6cm, possibly more.

Reference: British Caenozoic Fossils (NHM) plate 37, ISBN 1-898298-77-7.

08012009162100.jpg 

08012009162347.jpg 

(NB. scale in cm)


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"We try not to use the word insane, we prefer the term mentally hilarious..."



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Reply with quote  #3 
Name: Aequipecten opercularis.

Location: Specimens 1 and 2 are from the foreshore at Ramsholt, Suffolk, whilst specimen 3 is from the slippages at Walton-on-the-Naze, Essex.

Range: Coralline Crag - present day.

Diagnostics: Like many other equivalved scallops, the valves are moderately (but not overly) convex, and the hinge line is straight. The surface ornamentation consists primarily of prominent (equidistant) ridges that radiate outwards from the beak towards the anterior shell margin. Colouration varies widely, but commonly includes shades of brown, orange, yellow, cream, blue, and blue-green. Note that in Coralline Crag deposits, it is not uncommon to find A. opercularis embedded in, or attached to, various coral and bryozoa colonies, particularly in the case of the branching bryozoan Celleporaria palmata.

Size: Max diameter up to at least 5cm, though broken partials at both Ramsholt and Walton-on-the-Naze suggest it can grow somewhat larger.

Reference: British Caenozoic Fossils (NHM) plate 33, ISBN 1-898298-77-7.

09012009010226.jpg 

09012009011101.jpg 

09012009012300.jpg 

(NB. scale in cm)


-----------------
"We try not to use the word insane, we prefer the term mentally hilarious..."



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Reply with quote  #4 
Name: Centrocardita senilis.

Location: Found on the foreshore at Ramsholt, Suffolk.

Range: Coralline Crag - Red Crag.

Diagnostics: The valves are of equal size and highly convex. Shell ornamentation consists primarily of a series of alternating, equidistant grooves and ridges that radiate outwards from the umbo (beak) towards the anterior shell margin. Consequntly, the shell margin has a highly serrated edge with prominent teeth, and the umbo itself is placed somewhat off-centre within the valve, curving off either to the left or to the right depending upon the choice of valve. Internally, the adductor muscle scars are often quite pronounced, although there is an asymmetry here, with the muscle scar nearest to the umbo being considerably more prominent (as in the picture below, where the right-hand muscle scar is more defined).

Size: Max diameter up to at least 4cm, possibly more.

Reference: British Caenozoic Fossils (NHM) plate 35, ISBN 1-898298-77-7.

09012009130647.jpg 

09012009131640.jpg 

(NB. scale in cm)

-----------------
"We try not to use the word insane, we prefer the term mentally hilarious..."



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Reply with quote  #5 
Name: Cerastoderma parkinsoni.

Location: Found in the slippages at Walton-on-the-Naze.

Range: Red Crag.

Diagnostics: The valves are of equal size and highly convex. The shell wall is relatively thin for a bivalve of this size. Shell ornamentation consists primarily of a series of alternating, equidistant grooves and ridges that radiate outwards from the umbo (beak) towards the anterior shell margin, though the ridges are considerably wider than the grooves, and quite rounded in form. The shell margin is somewhat serrated, but far less so than in the case of Centrocardita senilis (in the preceding post). The umbo is slightly off-centre, but does not curve off to one side or the other. Internally, the adductor muscle scars are quite shallow, and there is a distinctive pattern of grooves and ridges running from the anterior shell margin towards the umbo, though these subside and smooth out quite rapidly at about a quarter of the distance between the two. 

Size: Up to at least 5.6cm max diameter.

Reference: British Caenozoic Fossils (NHM) plate 36, ISBN 1-898298-77-7.

09012009144151.jpg 

09012009145441.jpg 

09012009150335.jpg 

(NB. scale in cm)

-----------------
"We try not to use the word insane, we prefer the term mentally hilarious..."



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Reply with quote  #6 
Name: Venus casina.

Location: Found on the foreshore at Ramsholt.

Range: Coralline Crag - present day.

Diagnostics: The shell wall is often unusually thick for a bivalve of this size (less so in the example shown below), and the internal adductor muscle scars are quite distinctive and prominent, though both features may vary considerably due to stratigraphic distribution and natural species variance. Shell ornamentation consists primarily of a series of more-or-less evenly spaced growth ridges, though these often break off as in the specimen below, leaving a markedly less uniform pattern (see reference below for a more complete example). When the growth ridges break off, a vast number of compact growth striations (running from the umbo towards the anterior shell margin) become visible, as shown here. The umbo lies off-centre, and curves markedly either to the left or to the right depending upon the choice of valve. Internally, there are a multitude of small, prominent teeth along the anterior edge of the shell margin. The example shown here is typical of those found at Ramsholt, though this species exhibits considerable natural variance.

Size: Up to at least 4cm max diameter.

Reference: British Caenozoic Fossils (NHM) plate 36, ISBN 1-898298-77-7.

09012009151517.jpg 

09012009152000.jpg 

09012009153158.jpg 

09012009154619.jpg 

(NB. scale in cm)

-----------------
"We try not to use the word insane, we prefer the term mentally hilarious..."



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