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Mike from North Queensland

Ichthyosaur size calculation

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Mike from North Queensland

In my last couple of collecting trips I have found some larger than normal vertebra from the Australian ichthyosaur platyptergius australis.

What I am after is some literature that may enable me to calculate the length of an ichthyosaur based on the vertebra size.

I realise that the approximate body position the vertebrae will need to be a major part of the calculation.

Previously the larger vertebrae I found were around 80 mm diameter x 25 mm thick and quite often vertebrae from infants were also found with these so I had assumed fully grown.

The last couple of vertebra have measured 120 mm diameter x 40 mm.

This disparagement in size could be due to the younger / smaller females being more prone to dying during birth, they kept growing throughout there life or perhaps the alpha males were larger.

Thanks in advance for all input

 

Mike

Ichthyosaur vert DSC_0307 finished.JPG

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Mark Kmiecik

Apparently it is now Platypterigius longnami. I poked around for a short time but found no information that might make this type of calculation possible. I did see mention for the genus reaching a possible length of 7 meters, but nothing specific. From what I gathered it is known from 11 partial specimens. I don't know if enough of the necessary bits have been found that would make this kind of calculation any more than a very rough guesstimate. Good luck with this and let us know what you find.

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piranha
3 hours ago, Mark Kmiecik said:

Apparently it is now Platypterigius longnami...

 

 

Currently: Platypterygius australis

 

Platypterygius longmani is a junior synonym in:

 

Zammit, M., Norris, R.M., Kear, B.P. 2010

The Australian Cretaceous ichthyosaur Platypterygius australis: a description and review of postcranial remains.

Journal of Vertebrate Paleontology, 30(6):1726-1735

 

Kear, B.P., Zammit, M. 2013

In utero foetal remains of the Cretaceous ichthyosaurian Platypterygius: ontogenetic implications for character state efficacy.

Geological Magazine, 151(1):71-86

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Mark Kmiecik
19 hours ago, piranha said:

 

 

Currently: Platypterygius australis

 

Platypterygius longmani is a junior synonym in:

 

Zammit, M., Norris, R.M., Kear, B.P. 2010

The Australian Cretaceous ichthyosaur Platypterygius australis: a description and review of postcranial remains.

Journal of Vertebrate Paleontology, 30(6):1726-1735

 

Kear, B.P., Zammit, M. 2013

In utero foetal remains of the Cretaceous ichthyosaurian Platypterygius: ontogenetic implications for character state efficacy.

Geological Magazine, 151(1):71-86

I stand corrected. Thank you.

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Mike from North Queensland

Thanks for the replies thus far.

P. longmani was used for a while but further studies could not find any discernible variations to P. australis so the naming reverted back to P. longmani.

There is some evidence that there may be a second Ichthyosaur from Australia but to date nothing has been done and may only be due to growth changes.

I could not find any reference to establish size in Platypterguis australis other than the estimate that grew up to seven metres but that must have been based on something.

I was hopping that the comparison may have been done on a similar age Ichthyosaur from somewhere else in the world.  

 

Thanks all

Mike

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