Spinosauridae: The finished Saga

 Spinosauridae: The End

Different Specimens of S.aegyptiacus compared (Source: Wikipedia)

Before We Start

First of all I really apologise for the lack of uploads lately, my curriculum is really tight and I don't have time for many extracurricular activites. I do occasionally find time for other things but I spend a fair amount of it on an ebook I am writing, so be prepared!

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This post is not a correction of the other spinosauridae-related posts from last year, but rather a whole new one with more accurate information.

Introduction

The Spinosauridae is an awe-inspiring group of theropod dinosaurs that appeared during the Cretaceous Period, briefly 139 million years ago. The group is recognised by the general public as the group from which the Spinosaurus, the Baryonyx etc, originate, however, many other fascinating creatures are included, The group is seperated in two subgroups, Baryonychinae and Spinosaurinae, both containing a fair amount of related spinosaurids.

Phylogenetic Issues

*Note: This section is reffering to a controversial topic, so it should not be taken as an aswer to any question but rather as a method of informing the viewer of the ongoing discussion. Author's (my) personal opinions will be included   

Spinosauridae is a really diverse group yet its exact phylogenetics have been under discussion since the group's discovery. Many issues regarding the origin,validility or invalidility of specific genera have been up to debate for years, leaving open gaps in the spinosaurids's phylogenetic "tree"

 Sigilmassasaurus and Oxalaia

The above genera are parts of the group spinosaurinae that lived during the cenomanian stage of the cretaceous period ( Sigilmassasaurus: ~99-94 mya, Oxalaia: ~100.5- 93.9 mya). The validility of these above genuses has been up to debate, since both of them are described from fragmental specimens

(Holotype Specimen Of Sigilmassasaurus brevicolis. Source:Wikipedia)

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The specimens of Sigilmassasaurus were found in the Kem Kem fosil beds in Morroco. Although really fragmentary, paleontologists have figured out that the specimens belong to a spinosaurid. The genuses' validility has been disputed multiple times however, since a variety of other specimens from the same area which bring similar characteristics have been found to belong to Carcharodontosaurus. 

The only specimen of Oxalaia was found in the Brazilian Cajual Island in 1999. Oxalaia is just like the Sigilmassasaurus a really controversial spinosaurid, only known from fragmentary remains, this time of the premaxilla (a bone found in skull of reptiles, in the area of the upper jaw. Humans don't have this bone). A study conducted in 2020 suggests that the fossils of Oxalaia are too fragmentary to be considered of a different taxon and are rather a result of individual variation of the genus Spinosaurus.

Distribution Of Spinosaurids

Spinosauridae's distribution is in a level worldwide. Specimens have been found all over the world, almost in every continent (excluding North America and Antarctica). It has become apparent that spinosaurids mainly inhabited north Africa and Europe, yet some moved to South America. The Above digital map shows were the first fossils if each spinosaurid were found, as well as the stage if the Cretaceous Period that each appeared in, and can greatly help one understand their distribution around the globe. 

The Australian Spinosaurid

A fossil of a spinosaurid vertebra was recovered in Australia in 2011. The fossil belonged to a juvenile baryonyx, which is quite fascinating since no fossils of baryonychine spinosaurids have been found in South America as of now, meaning that baryonyx must have travelled through the then connected lands of Europe,  South America and then from Antarctica to Australia. Generally a fascinating thing to think about, and it only leaves more space for people to wonder what else will spinosaurids have under their name.

New Controversial Finds In The World of Spinosaurids

1. Irritator's Split Lower Jaw

In 2023 a study was made regarding the spinochinine spinosaurid Irritator challengeri. 

It was found that irritator's lower jaw (specifically it's dentary bones) could split apart and then would reveal some sort of a membrane, allowing the dinosaur to swallow fish more easily, like a modern pelican. There's an article on this blog regarding the topic, click here to view it.

2.Spinosaurus wasn't aquatic 

Spinosaurus aegyptiacus, according to a study conducted in 2022, was not a fully aquatic dinosaur but rather a shoreline hunter. The study claimed that spinosaurus's bones weren't dense enough to support it swimming, and that the big display on it's back would also disable the creature from swimming, however this study has now become outdated.

Thank you for Reading!

I again apologize for the lack of new content but I've been have a lot on my curriculum lately. Hope you enjoy, bye!

Sources of images: Wikipedia

Information sources: Wikipedia, Species new to science.