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Sea Urchin Fossil?


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Hello there all!

I have not been able to do much fossiling over the last few months as I have been busy with this and that, however in the last week I was able to take a couple of trips up to Mathesons Bay. The bay is situated in Leigh, north of Auckland and belongs to the Cape Rodney formation. The fossil bearing rocks in the bay are early Miocene, between 22 and 20 million years old (Otaian in New Zealand's geological scale). The specimen I'm wondering about was found in coarse sandstone, along with some quite nice little brachiopods ( in fact there is a piece of brachiopod attached to it). It is only a fragment but the piece has rows of knobs ranging from 2mm to 0.5mm in diameter running along its curved surface. There does not seem to be a clear pattern in regards the size of the knobs in each row, which leaves me wondering if it is a echinoid or not. However, it is possible the the variability in the knob's size is down to weathering, as the specimen is quite worn..

 

As far as I have read, the only echinoid known from the locality is Phyllacanthus titan, with that known from its fossilised  spines alone (a few fragments of which I found, one quite near the specimen in question). I am wondering if this piece is from Phyllacanthus titan, or some other type of sea urchin.

Thanks a lot!

 

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Here are a couple more pictures, the specimen is rather worn and a little difficult to make out I am afraid..

 

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-Lyall

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Hi,

 

I can't help you now. Could you clean your sea urchin ? I don't see enough details to determine even a family, in the view of the pic I can just say that it is about a regular sea urchin. It would be necessary to see ambulacres and pores (at the top of the sea urchin).

 

Coco

----------------------
OUTIL POUR MESURER VOS FOSSILES : ici

Ma bibliothèque PDF 1 (Poissons et sélaciens récents & fossiles) : ici
Ma bibliothèque PDF 2 (Animaux vivants - sans poissons ni sélaciens) : ici
Mâchoires sélaciennes récentes : ici
Hétérodontiques et sélaciens : ici
Oeufs sélaciens récents : ici
Otolithes de poissons récents ! ici

Un Greg...

Badges-IPFOTH.jpg.f4a8635cda47a3cc506743a8aabce700.jpg Badges-MOTM.jpg.461001e1a9db5dc29ca1c07a041a1a86.jpg

 

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Hi @Coco,

thank you for your reply. I'm not sure how much cleaning the fossil will help, as it is pretty beaten up, but I can give it a go:fingerscrossed:

 

@caterpillar,

that certainly looks quite similar to it! I'll do a bit more research on what sea urchins were around at the time in New Zealand. Thanks:dinothumb:

-Lyall

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