Macrocollum itaquii: An Insight Into Sauropodomorph Evolution

On the 21st of November 2018 new research was published in the Journal of The Royal Society about the discovery of a new species of dinosaur named Macrocollum itaquii. In this article I examine this dinosaur discovery and what it means for understanding early dinosaur evolution during the Triassic era.

It has been a while since I focused on a proper fossil discovery here on Jurassic Finds, as my last big article was a review of the dinosaur exhibits of the Natural History Museum in London. This article will once again be focusing on the latest fossil discoveries, with a focus on some intriguing dinosaur research in South America.

So If you didn’t already know palaeontologists in Brazil recently published some really exciting research in Biology Letters  on the 21st of November about the discovery of three new sauropodomorph skeletons, which have been identified as a new species of dinosaur named Macrocollum itaquii. The research about this amazing discovery was picked up by many Science and News websites these included Phys.org, Discover Magazine, Independent and the Express.

Skull in left lateral view
The skull of Macrocollum itaquii. (a) Skull in left lateral view (CAPPA/UFSM 0001a). (b) Skull in dorsal view (CAPPA/UFSM 0001a). (c) Skull in ventral view (CAPPA/UFSM 0001b). Image credit: Müller et al 2018.  

After reading the research I knew right away I wanted to cover the story here on Jurassic Finds. Little is known about sauropodomorph evolution due to the scarcity of well preserved dinosaur fossils and bones from the Triassic period. Which is why the discovery of Macrocollum itaquii is incredibly exciting, as it is the oldest long-necked dinosaur known to date. It is important not just as a dinosaur in it’s own right but as a gap filler in the early sauropodomorph phylogenetic tree.

Where were the fossils of Macrocollum itaquii found?

The three fossilized dinosaur remains (over 225 million years old) were found in the Late Triassic Beds of the Wachholz site near Agudo, Rio Grande do Sul in Brazil. This is part of the upper portion of the Candelária Sequence. Past research (Muller et al. 2015) into the fossil bearing quality of this Brazilian bonebed suggests a fossil locality that has one of the richest most complete sauropodomorph records from the Upper Norian (Upper/Late Triassic).

Some of the palaeontologists involved in the 2015 study were also involved in the most recent research on Macrocollum. The palaeontologists in the 2018 study noted that Macrocollum was smaller than it’s descendants. That they would have stood around five feet tall, walking on two legs and growing up to 12 feet in length. They would have weighed over 200 pounds and had very long necks, allowing these dinosaurs to reach the highest tips of vegetation such as gymnosperms (Yirka, 2018).

Macrocollum itaquii
Reconstruction of Macrocollum itaquii showing the discovered bones (in white). Image credit: Müller et al 2018 via Live Science.

The fossilized remains were also found all together suggesting the earliest evidence for social behaviour within sauropodomorphs. Two of the skeletons were found to be almost complete specimens with the third missing it’s head, with only partial remains of the neck (Tarlach, 2018). The specimens having been found in such close proximity together suggests that Marcocollum lived in groups.

What do these fossil discoveries mean for understanding the Triassic evolution of sauropodomorphs? 

The identification of this dinosaur within the phylogenetic tree is important for many reasons. The fossilized specimens show anatomical changes that have shaped the evolution seen in the already classified sauropodomorphs. They increased their size ratio of 230%, their long necks became more established becoming twice as long as those of basal taxa (Muller et al. 2018). Such evolutionary evidence of development can help palaeontologists to fill in the blanks of the sauropodomorph phylogenetic family tree increasing our understanding of dinosaur evolution and the evolutionary trends seen during the Triassic era.

Phylogentic Position
In this time-calibrated consensus tree the phylogenetic position of Macrocollum itaquii is depicted as well as some evolutionary trends along the lineage. Image credit: Müller et al 2018.

I hope you have all enjoyed reading this article. The research that is being  undertaken on sauropodomorphs in the Candelaria Sequence is very fascinating, hopefully more sauropodomorph remains will be found in the near future helping to establish further backstory to these unusual dinosaurs.

You can keep up to date with all my latest articles by following the blog where you can receive emails of my latest posts. If you go to the home page and click the follow tab you can fill in your email address and be subscribed.

I look forward to sharing more about the latest fossil discoveries with you all very soon!

 

References

 

Rodrigo Temp Müller, Atila Augusto Stock da Rosa, Lúcio Roberto da Silva,
Alex Sandro Schiller Aires, Cristian Pereira Pacheco, Ane Elise Branco Pavanatto,
Sergio Dias-da-Silva (2015) Wachholz, a new exquisite dinosaur-bearing fossiliferous site from the Upper Triassic of southern Brazil. Journal of South American Earth Studies 61 120-128 https://doi.org/10.1016/j.jsames.2014.10.009

 

Rodrigo Temp Müller, Max Cardoso Langer, Sérgio Dias-da-Silva (2018) An exceptionally preserved association of complete dinosaur skeletons reveals the oldest long-necked sauropodomorphs. Biology Letters 14 20180633; DOI: 10.1098/rsbl.2018.0633

 

Tarlach G. (2018) Oldest Long-Necked Dinosaur Found in Brazil, [online] Discover Magazine, Available from: http://blogs.discovermagazine.com/deadthings/2018/11/20/dinosaur-brazil/#.XAF0bfZ2tPZ [Accessed 30th November 2018]

 
Yirka B. (2018) Three ancient skeletons, ancestors of giant dinosaurs, unearthed in Brazil, [online] Phys.org, Available from: https://phys.org/news/2018-11-ancient-skeletons-ancestors-giant-dinosaurs.html [Accessed 30th November 2018]

 

 

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