Meet Meraxes gigas, a new South American carcharodontosaurid

[Concavenator]

A new South American Carcharodontosauridae known from what appears to be fairly good remains. Here's the skeletal from the paper:



Here's the abstract, though I was able to download the whole paper thanks to my university, if anyone needs it, don't hesitate in asking me!

@Halichoeres was this the carcharodontosaurid genus you said a friend of yours was working on its description?

PS. 1 Literally every media feeling the need to mention Tyrannosaurus in every single new theropod discovery.



PS. 2 Another pop-culture inspired genus name. 

[Halichoeres]

Yep, that's the one (for anyone else reading, here's what he's talking about: https://dinotoyblog.com/forum/index.php?topic=3390.msg294825#msg294825). The senior author said on Twitter today about Meraxes and its close relatives: "these species differ mainly in details of facial bone ornamentation and vertebral pneumatics," in other words, details that would be scarcely discernible externally, if at all. I'm sure lots of people will be wanting figures of Meraxes, but those figures will just look like other members of Giganotosaurini.

[Baryonyx]

Pop culture derived names are so unbearably cringeworthy!
Forgive me, I know it's a matter of personal opinion.

[Duna]

That's a very complete dinosaur!! 

[Gwangi]

I wasn't aware that Meraxes was a pop culture name until I Googled it. It doesn't surprise me that a lot of scientists are also pop culture nerds. Most of my pets have names that are pop culture references, I might do the same with naming a prehistoric animal if given the chance. You gotta be clever about it though. Most of them are pretty bad names. Thanos, Dracorex, Zuul...no thanks. Meraxes isn't too bad.

[Flaffy]

I wouldn't mind a figure of this. I don't see why we shouldn't have a figure of it considering its so complete compared to other highly requested, yet fragmentary Carcharodontosaurids like Tyrannotitan.

The pronounced crests should open the door for some interesting design choices when it comes to keratin structures.

[GojiraGuy1954]

It also seems to have an enlarged toe claw, like a cassowary.

[Flaffy]

Another point of interest is how reduced the forelimbs were. And quoting Peter Makovicky:

"With almost complete arms, Meraxes exhibits a degree of forelimb reduction comparable to late diverging tyrannosaurids and abelisaurids."

[Leyster]

@Halichoeres not exactly. Those differences you mention are the ones you can compare with other carcharodontosaurids. Meraxes still has plenty of traits which were unknown before, like the arm reduction, the enlarged second toe claw and the head shape (since in 2022 they keep using the old Giganotosaurus head for models).

[Faelrin]

Wow finally another carcharodontosaurid with more substantial remains aside from Acrocanthosaurus and Concavenator. I definitely would prefer a figure of this over Gigantosaurus and Carcharodontosaurus, merely on the basis of it being more complete.

Some other info of interest I gleaned from the wikipedia page:

It was initially found in 2012. Kind of sad the remains took a decade to be described and named.

It may have lived up to 53 years old, and completed maturity between 30-40 years.

It lived in the Huincul Formation, alongside animals like Mapusaurus, Skorpiovenator, Gaulicho, Argentinosaurus, and more.

Edit: Hold up, am I reading that skeletal diagram correctly? Was it found with a fifth digit, or at least a claw? That's highly unusual among most theropods. Also wow look how reduced the claw on digit 1 of the hands is (and the others). That's interesting. Plus the enlarged claw on the second digit of the foot is also a first time on such a large theropod? I really dig how different this one is when you get into the little stuff that make it up.

Edit 2: Okay the paper didn't say anything metatarsal V being a claw or the like, but they did mention it was curved (which is what I took notice of, and mistook it for a claw) and articulates with metatarsal IV. So that question is solved. Also they did mention that the claw on the second digit of the foot has a sharp ventral edge then the other claws (which were rounder).

Also further into the paper they provide estimates for Giganotosaurus skull, based on the decent remains Meraxes has (which also has a skull length of 127cm). They estimate it to be about 163.4 cm, with a give or take between 157.8 and 168.8 cm, with a 95% probability. I wonder if there will be new skeletals with this information (unless there is no need)? They also provide measurements for other large theropod skulls that are complete or near complete, including Acrocanthosaurus (123 cm), Deinocheirus (102 cm), and "Sue" the T. rex (140 cm), for comparison. I think this information will be useful for folks on the former here, especially anyone doing scale comparisons while using the skull.

[Sim]

This is a great discovery, although I confess I tend to find allosauroids boring and this one isn't an exception.  Sorry to those who like them!  My understanding is Meraxes doesn't have a fifth toe, just the vestigial remains of one which is normal for theropods.  I've been seeing it in Scott Hartman's skeletals since a long time now.

[Concavenator]

Interestingly, in the phylogenetic analysis presented in the paper, Neovenator is recovered as a Carcharodontosauridae.

In that case, I think its remains are relatively decent compared to other members of it family (save for Acrocanthosaurus, Concavenator or Meraxes).

[andrewsaurus rex]

The evolutionary tendency for arm reduction in these large theropod lines is very interesting.  You wouldn't think there would be a significant evolutionary advantage in having relatively tiny arms get even smaller through time.  Especially if the arms were used during copulation.   Yet in tyrannosaurids, abelisaurids and carcharodontosaurids  the trend is established.

[KeU]

Do we have other fossil records of Carcharodontosauridae feet?
Curious if the enlarged 2nd toe claw is unique to the genus or might be a common family trait.