All about dinosaurs, fossils and prehistoric animals by Everything Dinosaur team members.
2 01, 2023

Sauropod Dinosaurs Did Not Have Supersonic Tails

By | January 2nd, 2023|Adobe CS5, Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles|0 Comments

A recent study published in the academic journal “Scientific Reports” refutes the idea that some long-necked herbivores had supersonic sauropod tails. The controversial idea that some dinosaurs could lash their tails like a whip creating a supersonic crack as the tail travelled faster than the speed of sound has been refuted in newly published research. Instead, the researchers suggest that the tail of diplodocids such as Apatosaurus, Brontosaurus and Diplodocus could still play a role in defence, producing a painful blow to deter an attacker. It is also suggested that these long, whip-like tails could have been used in intraspecific combat.

Apatosaurus scale drawing.
Scale drawing of Apatosaurus (A. ajax). Note the long, whip-like tail. New research suggests that these long tails could not be used to create a “crack” as they broke the sound barrier. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

Supersonic Sauropod Tails

A sauropod clade, the Flagellicaudata are characterised by their extremely long tails. This clade includes the Diplodocidae family and the closely related Dicraeosauridae. Although complete fossil sauropod tails are extremely rare, palaeontologists have a good idea of the anatomy of a typical diplodocid tail. It consisted of approximately eighty caudal vertebrae, that gradually decrease in size and morphological complexity towards the tail tip. There are approximately ten larger posterior vertebrae, followed by forty or so intermediate bones with finally around thirty progressively smaller rod-like caudal vertebrae.

Earlier studies had suggested that the tail could be whipped, and the tip would travel so fast (in excess of 500 metres per second), this action would break the sound barrier and produce a loud sound. This speedy tail would cause a significant injury should it come into contact with another dinosaur.

However, this new study used three-dimensional models and computer analysis to assess the stress on the bones, ligaments and soft tissues. They concluded that the maximum tip velocity generated would be around thirty metres a second, nowhere near the 330 metres per second required to break the sound barrier.

Eofauna Diplodocus scale model
The Eofauna Diplodocus carnegii model measures around 60 cm in length and stands 11 cm tall. It is a 1/40th scale model. Most of the model’s length is made up of the long tail. Diplodocids are members of the Flagellicaudata clade.

The picture (above) shows the recently introduced Eofauna Scientific Research Diplodocus carnegii replica. When shown in lateral view, the extremely long tail can be seen.

To view the range of models and figures in the Eofauna series: Eofauna Scientific Research Models.

An Effective Weapon

Whilst the researchers conclude that the effect of friction on the musculature and aerodynamic drag would prevent the tail tip from reaching a speed capable of breaking the sound barrier, the pressure applied by the terminal section would not be enough to break bones or lacerate dinosaur skin, but it could still deliver a painful blow.

In summary, the scientists suggest that sauropod tail use remains speculative, these tails could have been used in intraspecific combat, or perhaps as a weapon against predators. Similarly, the use of the tail as a tactile element to retain herd cohesion is equally plausible.

The scientific paper: “Multibody analysis and soft tissue strength refute supersonic dinosaur tail” by Simone Conti, Emanuel Tschopp, Octávio Mateus, Andrea Zanoni, Pierangelo Masarati and Giuseppe Sala published in Scientific Reports.

2 01, 2023

The Evolution of the Backbone

By | January 2nd, 2023|Adobe CS5, Dinosaur and Prehistoric Animal News Stories, Main Page, Palaeontological articles|0 Comments

The evolutionary development of the vertebral column has been extensively researched. Numerous fossil specimens have been studied as scientists pursue a greater understanding of the evolution of the backbone. Recently, a new scientific paper has been published in “Scientific Reports” that outlines the evolutionary development of ossification patterns in four-legged vertebrates.

Research from the Museum für Naturkunde

The study was undertaken by scientists from the Museum für Naturkunde (Berlin, Germany). Antoine Verrière and his colleagues were able to reconstruct the patterns of how the bones in the vertebral column formed in the ancestor to all land vertebrates based on a large dataset compiled from studies of extant and extinct vertebrates. The dataset also included new information on the spine of Mesosaurus tenuidens, widely regarded as the first reptile to adapt to an aquatic existence, back in the Permian some 300 million years ago.

Evolution of the Backbone.
Understanding the evolution of ossification patterns in the backbones of four-legged vertebrates. Picture credit: Verrière and Fröbisch.

The Evolution of the Backbone

Lead author of the paper, Antoine Verrière explained that M. tenuidens had a long snout and a powerful tail that propelled it through the water. It inhabited an inland sea that once existed in the southern region of the supercontinent Pangaea.

The palaeontologist added:

“On some rare juvenile specimens, we observed that the neural arches, the spines sitting on top of the main part of a vertebra, were closing from head to tail as the animals grew, much like a zipper. We wanted to understand how this pattern would fit in the evolutionary history of land vertebrates, but quickly realised there was surprisingly little information available. So, we decided to investigate this ourselves!”

Four Major Developmental Patterns in Backbones of Amniotes

The research team looked at four of the major developmental patterns in the backbones of amniotes (mammals, reptiles and birds):

  • The ossification of the centrum (the main body of a vertebra).
  • The ossification of paired neural arches.
  • The fusion of the initially forming paired neural arch elements into one spine.
  • The fusion of neural arches with the centrum, also called neurocentral fusion.

Statistical analysis was used to model how these different patterns changed from the Permian through to today, their work roughly covering the evolutionary history of land-living vertebrates excluding amphibians. With this research the team could reconstruct the patterns in the common ancestor to all land vertebrates.

Co-author of the study, Professor Jörg Fröbisch (Museum für Naturkunde) commented:

“What surprised us the most was that these patterns appear to have been relatively stable for the last 300 million years. Modern and extinct vertebrates are enormously diverse in terms of their body shapes and lifestyles and the elements of their vertebral columns are organised in complex units that differ greatly between species. Nevertheless, the ossification patterns were much more conservative than was expected from the great morphological diversity.”

Edmontosaurus skeleton.
Duck-billed dinosaur on display showing the vertebral column. Despite vertebrates having extremely diverse body shapes and complex spines the observed ossification patterns were much more conservative than expected. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

Some Deviations Identified

Although the patterns studied show relative stability through deep geological time, some deviations were identified. Notably, birds, mammals, and members of the Squamata Order (snakes and lizards) each evolved their own specific modes of vertebral ossification, which differ from the ancestral condition in amniotes. Yet again, within these groups, the patterns were also surprisingly stable.

Fellow co-author Professor Nadia Fröbisch (Museum für Naturkunde) explained:

“Ostriches and seagulls, for instance, have very different anatomies and lifestyles, but their vertebral columns ossify in similar ways. This shows that some changes can be observed between the major lineages of land vertebrates, but within each of the main lineages, spine development remained rather stable again.”

This study demonstrates how studying modern animals alongside their ancient ancestors can provide a much deeper understanding of the evolutionary development of key anatomical structures.

Everything Dinosaur acknowledges the assistance of a media release from the Museum für Naturkunde (Berlin) in the compilation of this article.

The scientific paper: “Regionalization, constraints, and the ancestral ossification patterns in the vertebral column of amniotes” by Antoine Verrière, Nadia B. Fröbisch and Jörg Fröbisch published in Scientific Reports.

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