Profile cover photo
Profile photo
Darius Nau
I’m a student of earth sciences, with primary interests in vertebrate palaeontology, anatomy and evolution.
I’m a student of earth sciences, with primary interests in vertebrate palaeontology, anatomy and evolution.
About
Posts

Post has attachment
Just a data table for something I posted previously.
References are the same as here: https://plus.google.com/117004548610274606425/posts/gLvSaksFaUc
Photo

Post has attachment
Since it’s #FossilFriday , here are some pieces from my collection (or the part of it that I took with me when I moved, anyway).
Some of my own findings:
• Ammonites, crinoids, bellemnite and ichthyosaur vertebra from Lyme regis, Jurassic coast, England.
• A cenozoic clam from Albufeira, Algarve, Portugal.
• Piece of pyritised charcoal from the plant debris beds of the isle of wight, found during the SVPCA field trip (Admittedly not a vertebrate. But everybody dreams of finding the dinosaur bones…).

Acquired through other means:
•Teeth of Carcharias hopei, Otodus obliquus and Carcharocles cf. subauriculatus or megalodon (purchased)
Dastilbe elongatus (purchased)
• Fragmentary dinosaur bone (Morrison Formation) and eggshell (acquired during a fossil preparation course).
PhotoPhotoPhotoPhotoPhoto
2015-09-25
15 Photos - View album

Post has attachment
UPDATE:
Can you imagine there are no less than 6 (and probably more) regression equations to estimate body mass from total length in Great White sharks? That’s a pretty impressive number, so I decided to make use of it and included all the ones I could verify.

Methods (Estimates and silhouettes):
• Great white shark scaled at 5m (estimated mass 1084-1294kg, with a mean of 1195kg)
• Average adult C. megalodon of 14m, based on the data set from Pimiento & Balk 2015 and assuming individuals above 11.9m to be adults.
• Estimated size of a large adult, based on a very large tooth (probable upper lateral, 12.6cm wide and 15.8cm tall, with a crown height of 11.9cm) from Denmark that was found in association with some vertebrae (Bendix-Almgreen 1983).
Mean estimates (assuming a position within the anteriormost 3 lateral tooth files) are based on an extrapolated tooth row length and Lowry et al.’s formula (2009, tooth-row length extrapolated for each of the positions and assuming 15% interdental spacing) and on Shimada’s crown height regressions reported by Pimiento et al. (2010) were congruent in this case.
The specimen is among the largest in the literature, and certainly the largest that is indicated to have come from a dead shark.
This also coincides with other estimates that have at various times been the highest in the literature (though currently that title goes to an estimated 17.9m shark reported in Pimiento & Balk 2015), namely the highest figure that based on data considered reliable by Gottfried et al. (1996), and the largest specimen described by Pimiento et al. (2010).

The silhouettes are to scale and centered on their respective mean mass estimates.

Mass estimates were derived from published length-mass regressions (formulae given on graph) for Carcharodon carcharias:
Gottfried et al. 1996:
3.29*10^-6*(100*x)^3.174
Kohler et al. 1995:
7.5763*10^-6*(0.9442*(100*x)-5.7441)^3.0848
Tricas & McCosker 1984:
3.8*10^-6*(100*x)^3.15
Mollet & Cailliet 1996:
7.914*x^3.096
Casey & Pratt 1985:
4.80376*10^-6*(100*x)^3.09497
McClain et al. 2015:
10^0.99*x^3.00


–––References:
   Bendix-Almgreen, Svend E. (1983): Carcharodon megalodon from the Upper Miocene of Denmark, with comments on elasmobranch tooth enameloid: coronoïn. Bulletin of the geological Society of Denmark, 32 pp. 1-32.
   Casey, John G.; Pratt, Harold L. (1985) Distribution of the White Shark, Carcharodon carcharias, in the Western North Atlantic. Memoirs of the Southern California Academy of Sciences, 9 (Biology of the White Shark, a Symposium.), pp. 2-14.
   Kohler, Nancy E.; Casey, John G.; Turner, Patricia A. (1995): Length-Length and Length-Weight Relationships for 13 Shark Species from the Western North Atlantic. Fishery Bulletin, 93 pp. 412-418.
   Lowry, Dayv; Castro, Andrey L. F. de; Mara, Kyle; Whitenack, Lisa B.; Delius, Bryan; Burgess, George H.; Motta, Philip: (2009): Determining shark size from forensic analysis of bite damage. Marine Biology, 156 pp. 2483-2492.
   McClain, Craig R.; Balk, Meghan A.; Benfield, Mark C.; Branch, Trevor A.; Chen, Catherine; Cosgrove, James; Dove, Alistair D.M.; Gaskins, Lindsay C.; Helm, Rebecca R.; Hochberg, Frederick G.; Lee, Frank B.; Marshall, Andrea; McMurray, Steven E.; Schanche, Caroline; Stone, Shane N.; Thaler, Andrew D. (2015): Sizing ocean giants: patterns of intraspecific size variation in marine megafauna. PeerJ, 3 (715) pp. 1-69.
   Mollet, Henry F.; Cailliet, Gregor M. (1996): Using Allometry to Predict Body Mass from Linear Measurements of the White Shark. In: Klimley, Peter A.; Ainley, David G.: Great White Sharks: the biology of Carcharodon carcharias. San Diego, pp. 81-89.
   Pimiento, Catalina; Balk, Meghan A. (2015): Body-size trends of the extinct giant shark Carcharocles megalodon: a deep-time perspective on marine apex predators. Paleobiology, 41 (3), pp. 479-490.
   Pimiento, Catalina; Ehret, Dana J.; MacFadden, Bruce J.; Hubbell, Gordon (2010): Ancient Nursery Area for the Extinct Giant Shark Megalodon from the Miocene of Panama. PLoS ONE, 5 (5), pp. 1-9.
   Tricas, Timothy C.; McCosker, John E. (1984): Predatory Behaviour of the White Shark (Carcharodon carcharias) with notes on its biology. Proceedings of the California Academy of Sciences, 43 (14), pp. 221-234.
Photo
Photo
2015-09-23
2 Photos - View album

Post has attachment
UPDATE: Read this instead: https://plus.google.com/117004548610274606425/posts/gLvSaksFaUc
It is more comprehensive  and includes everything already covered here.

Methods:
(Estimates and silhouettes)
• Great white shark scaled at 5m (estimated mass 1084-1294kg)
• Average adult C. megalodon of 14m, based on the data set from Pimiento & Balk 2015
• Estimated size for a large adult, based on a very large tooth (probable upper lateral, 12.6cm wide and 15.8cm tall, with a crown height of 11.9cm) from Denmark that was found in association with some vertebrae (Bendix-Almgreen 1983). Mean estimates (assuming a position within the anteriormost 3 lateral tooth files) based on an extrapolated tooth row length and Lowry et al.’s formula (2009) and on Shimada’s crown height regressions reported by Pimiento et al. (2010) were congruent.
This also coincides with other estimates that have at various times been the highest in the literature (though currently that title goes to an estimated 17.9m shark reported in Pimiento & Balk 2015), namely the highest figure that based on data considered reliable by Gottfried et al. (1996), and the largest specimen described by Pimiento et al. (2010).

The silhouettes are to scale and centered on their respective mean mass estimates, with the tail ends at their respective lengths.

Upper and lower mass estimates were derived from two length-mass regressions (formulae given on graph) for Carcharodon carcharias (Casey & Pratt 1985, Kohler et al. 1995).

–––References:
   Bendix-Almgreen, Svend E. (1983): Carcharodon megalodon from the Upper Miocene of Denmark, with comments on elasmobranch tooth enameloid: coronoïn. Bulletin of the geological Society of Denmark, 32 pp. 1-32.
   Casey, John G.; Pratt, Harold L. (1985) Distribution of the White Shark, Carcharodon carcharias, in the Western North Atlantic. Memoirs of the Southern California Academy of Sciences, 9 (Biology of the White Shark, a Symposium.), pp. 2-14.
   Kohler, Nancy E.; Casey, John G.; Turner, Patricia A. (1995): Length-Length and Length-Weight Relationships for 13 Shark Species from the Western North Atlantic. Fishery Bulletin, 93 pp. 412-418.
   Lowry, Dayv; Castro, Andrey L. F. de; Mara, Kyle; Whitenack, Lisa B.; Delius, Bryan; Burgess, George H.; Motta, Philip: (2009): Determining shark size from forensic analysis of bite damage. Marine Biology, 156 pp. 2483-2492.
   Pimiento, Catalina; Balk, Meghan A. (2015): Body-size trends of the extinct giant shark Carcharocles megalodon: a deep-time perspective on marine apex predators. Paleobiology, 41 (3), pp. 479-490.
   Pimiento, Catalina; Ehret, Dana J.; MacFadden, Bruce J.; Hubbell, Gordon (2010): Ancient Nursery Area for the Extinct Giant Shark Megalodon from the Miocene of Panama. PLoS ONE, 5 (5), pp. 1-9.
Photo

Post has attachment
Some stuff from Seacity Museum's Dinosaur Encounter-exhibit, Southampton, including a newly studied polacanthid specimen you can read about in the SVPCA abstracts.

Once again, please excuse my being a bad photographer.
#FossilFriday
PhotoPhotoPhotoPhotoPhoto
11/09/2015
8 Photos - View album

Post has attachment
Megaloceros
#FossilFriday  
PhotoPhotoPhoto
2015-09-11
3 Photos - View album

Post has attachment
The first snake.
A sort of Archaeopteryx of squamata if you will (though of course depending on your definition of "bird", Archaeopteryx may neither be the earliest nor the most basal bird, but anyway…), Tetrapodophis amplectus is both the earliest known snake and the only one with four limbs. This phylogenetic placement is apparently well-supported by its characters (as Longrich put it so eloquently at SVPCA, even its legs look like those of a snake, and no, that’s not a contradiction).

Here’s a picture of the fossil:
http://cdn4.sci-news.com/images/enlarge2/image_3057_2e-Tetrapodophis-amplectus.jpg

And here a nice life reconstruction:
http://www.slate.com/content/dam/slate/articles/video/video/2015/07/snake_arms_tetrapodophis_amplectus_fossil_discovery_shows_lizard_snake_ancestor/snakearms.jpg.CROP.promo-xlarge2.jpg

Apart from that, which is amazing enough, Tetrapodophis not adapted for swimming at all, lending credibility to the hypothesis that snakes evolved from ancestrally terrestrial lizards that adapted for a burrowing lifestyle. Also its tooth and body morphology suggests a macropredaceous diet of other vertebrates, which it killed by constriction. Its legs may have been used as a tool for prey restraint.

Post has attachment
Some of the nicer examples of fossilized ornithopod and (in the last one) sauropod foot casts on the isle of wight.
#fossilfriday
PhotoPhotoPhotoPhoto
04/09/2015
4 Photos - View album

Post has attachment
Neovenator salerii in the Dinosaur Isle museum, Isle of Wight. Very sorry for the terrible image quality, turns out I'm a bad photographer.
#fossilfriday
PhotoPhotoPhotoPhoto
04/09/2015
4 Photos - View album

Post has attachment
Some photos I just took at the Goldfuß Museum (University of Bonn).

The highlights are the ichthyosaurs (A Stenopterygius and an Ophtalmosaurus, the latter of which, as you can see, is unfortunately very hard to photograph), the Cryptoclidus and the old systematic collection, which houses a huge number of invertebrate specimens.
PhotoPhotoPhotoPhotoPhoto
2015-08-27
17 Photos - View album
Wait while more posts are being loaded