(Inconclusive) News: A Spinosaurus arm has been discovered!

Yesterday after class, Professor Holtz told me about the discovery (a tricky one to say the least, but still a discovery) of a Spinosaurus arm. I had to look for it online, and a cast was made by DinoLab. 

Here's a pic from DinoLab's Instagram page (Gramho):

From what I can tell, and from what professor Holtz said to me, one of the fingers is really long for some odd reason. I think it's the third digit, based on the photo. The fingers in general are long, and I think they appear to have been flexible (well, as flexible as theropod hands could have been). The claws are actually really short for a spinosaur. Baryonyx (including Suchomimus if you want to keep the two genera separate) had huge, and robust, claws at the end of its fingers, especially on the thumb. Spinosaurus' claws are shorter and thinner.

What's even more surprising is the lower arm. The radius and ulna are really short! The humerus is long, but why are the lower arm bones barely half the length of the humerus? Well, I asked professor Holtz if it appeared that larger carnivorous theropods (like tyrannosaurids and carcharodontosaurids) grew larger heads and tossed their arms aside, and he said that it appears to be going in that route. This is so cool! Tyrannosaurids were not the only large carnivorous theropods that be going for smaller arms. It's just so surprising to see Spinosaurus going in this route because it's always been shown to have large arms. They were a composite of other spinosaurids, but it just seemed natural. Spinosaurus is a spinosaur, so naturally it would have had large arms like its relatives. Now, it appears to be the opposite. Spinosaurus' arms were not as small as T. rex's, but they have shrunk.

Interestingly, the radius and ulna are short but thick. Could this have been for support on land? Luis V. Rey suggests that Spinosaurus used its forelimbs to help it walk on land (not knuckle-walking, but actually spraying its fingers out like a walrus). Perhaps these long fingers did that? I don't know, but at this point I'm just going along for the ride. Spinosaurus is that one dinosaur now that just keeps surprising us!

I never knew that I would be so enthralled by a dinosaur that I grew up hating thanks to Jurassic Park III!

Here's another picture of the hand compared to a full-grown woman for scale (The Zone @91-3, 9/2/20):

It really is smaller than the reconstruction (Kenneth Chang, 2014):

Update: I actually got in contact with Luis V. Rey, and we talked about the Spinosaurus arm. He said that some of the arm bones (like the wrists) are still unknown, but there is more evidence yet to be published that points to Spinosaurus being FULLY aquatic!

Here's a pic of our conversation:

This proves that Spinosaurus is the gift that keeps on giving!

Update (4/23/21): The arm is basically a composite. More information coming in the future. 

Update (6/12/21):
According to Paleontologist Roberto Diaz Sibaja, also known as Palaeos, says that the arm is a composite. The only bones that seem to be real, according to what DinoLab have said, are the metacarpals, phalanges, and the radius and ulna but they are partially complete. The humerus is totally fake. There is also some criticism towards the third finger being way too long, but it's not conclusive.

All in all, the arm is not totally trustworthy. Perhaps the metacarpals and phalanges are real, along with the partial radius and ulna, but I would take this with a grain of salt. 

Here's everything that Mr. Sibaja said on his FaceBook post:

Links:
DinoLab:
Instagram (Gramho):
https://gramho.com/media/2535465340537444071

Facebook:

https://m.facebook.com/dinolabinc/posts/our-spinosaurus-arm-is-still-on-display-we-arent-sure-how-much-longer-we-are-goi/885524165571071/

Twitter:

https://mobile.twitter.com/DinoLab_Inc/status/1322305140020269058

The Zone @91-3:
Photo:
https://images.app.goo.gl/FYeo7rjhQr6cPLja7
Website:
https://www.thezone.fm/2020/09/02/geekout-dino-lab-spino-arm/
Kenneth Chang (2014):
https://www.nytimes.com/2014/09/12/science/a-nomads-find-helps-solve-the-mystery-of-the-spinosaurus.html
Photo:
https://images.app.goo.gl/19ScuGkueXHXFEFB9
My Conversation with Luis V. Rey:
"The ongoing Spinosaurus Saga... now a nesting ground." 1/24/2021:

https://luisvrey.wordpress.com/2021/01/24/the-ongoing-spinosaurus-saga-now-a-nesting-ground/
Mr. Sibaja (Palaeos):
Facebook Post:

https://m.facebook.com/PalaeosPag/photos/a.157631294723661/1059058504580931
Blog:

https://palaeos-blog.blogspot.com/?m=0