A recent study published in Palaeontologia Electronica finds spinosaurid dinosaurs regrew their teeth unusually frequently, giving new insight into the dinosaurs’ dietary habits and explaining some puzzling phenomena in the fossil record.
Spinosaurs, the family of dinosaurs including the famous Spinosaurus, were remarkable creatures, from their enormous size to their crocodile-like skulls to the iconic sail on their backs. Like all reptiles, these dinosaurs had constant tooth replacement. This means that like humans, dinosaurs lost their teeth and they got replaced with new ones. However, instead of losing only one set of “baby teeth,” the dinosaurs continued losing and replacing teeth constantly throughout their lives, just like sharks and many other living creatures.
In a museum filled with towering dinosaurs, six small trilobites tell a big story. Paleontologists Russell Bicknell and Brayden Holland from University of New England, NSW documented evidence of injuries on trilobite fossils at the Royal Tyrrell Museum of Paleontology in Alberta, Canada, providing clues about predator-prey relationships in the Cambrian Period.
Trilobites were one of the oldest groups of arthropods—animals with exoskeletons and joint-legs, that includes insects and crustaceans. “A trilobite kind of looks like a slater (an isopod),” said Dr. Bicknell, “but has an exoskeleton that is made out of calcium carbonate, literal rock! And often they have a lot more spines than modern day isopods.”
Modern paleontology is exciting stuff. Once upon a time paleontology largely consisted of a team of dusty professors and college students baking in the summer heat as they carefully (and sometimes not so carefully) pried fossil bones, shells, and traces from their rocky tombs. It was grueling and unforgiving work. Still in its infancy, 19th and early 20th Century paleontology concerned itself with broad questions, e.g. “What is this animal?”, “What is it related to?”, “When did it live?”, “How big was it?” While some paleontology is still conducted this way (it certainly is in popular media), modern tools now allow paleontologists and other researchers to ask and answer questions they never dreamed would be possible only a few short decades ago.
In a July 2020 study in Palaeontologia Electronica, paleontologist Adiël A. Klompmaker and colleagues identified several Mesozoic crab specimens from sponge and coral-associated limestones in Europe. The researchers described six new taxa, reassigned several others, and documented some spectacular finds.
Fossils not only show us what ancient animals looked like, but also provide clues about how they lived. This is especially true for fossilized jaws and teeth, which tell a remarkable story of both what a species ate and how it ate. In a recent paper published in Palaeontologia Electronica, Dr. Annalisa Berta and Dr. Agnese Lanzetti used fossil data to track how marine mammals’ feeding strategies evolved over their 50-million-year history, providing a useful reference for studying drivers of diversity in the past, present, and future.
Tube Microstructure May Help Identify Eocene Marine Worms
Identifying organisms to genus or species level in the fossil record can be difficult. Often the characters that biologists use to identify modern species are absent or obscured in their fossil relatives. Think of how much more difficult a lion is to tell apart from a tiger without the luxury of flesh and fur to identify them, and you begin to get the idea (Christiansen 2008). Fossil animals rarely possess soft tissues and even more rarely possess exterior patterning (as in the lion/tiger example). We know, however, that there is a very big difference between a lion and tiger and that the same is likely true for fossil animals, in that they may appear superficially similar but should they be once again dressed in their soft parts, their identities as different species may become readily apparent. Because of this conundrum, any trait that can be easily and consistently identified in the fossil record and can help distinguish between fossil species is incredibly valuable.
Imagine you’re a snail living on the ocean floor…during an Ice Age. The sea temperature is drastically rising and falling as the Earth enters phases of glaciation and warming. The sea level is changing too, making your habitat deeper or shallower and often changing its structure entirely. How do species fare in this ever-changing world? And is their fate linked to their environment?
A sabre-toothed cat from Brazil
A recent paper in Palaeontologia Electronica (PE) by Dr. Artur Chahud describes a sabre-toothed cat specimen from the Cuvieri Cave of eastern Brazil. Caves are ideal places to find fossil specimens. The vertical cavities of this particular cave serve as “traps” for unsuspecting animals walking along the ground surface. After falling in it can be almost impossible to get out. Caves are also great at preventing erosional processes which would normally weather remains found at the surface, which is why there are often fossils of varying ages within the same cave. Inside the Cuvieri Cave, recent specimens of peccary, rodent, deer, and small reptiles are found alongside extinct specimens of Xenarthrans, ground sloths, Cuniculus (an extinct rodent), and Pleistovultur (an extinct vulture).
Investigating CT Scans as a Palaeontology Research Tool
You are probably familiar with a computed tomography (CT) scan; that medical machine that takes a bunch of x-ray scans of a person’s internal anatomy. If you haven’t had a CT scan yourself, you most likely know someone who has. CT scans are a great non-invasive technique that can be used to diagnose internal injuries and disease. What you may not know, is that CT scans can also be useful to look at structures of fossils.
Dr. Rosie Oakes and her colleagues recently published an article in Palaeontologia Electronica on how CT scans can best be used for palaeontology research. “If you want to see inside an object but you don’t want to (or aren’t allowed to) smash it with a hammer, you can use a CT scanner” says Dr. Oakes.
Introducing our new Executive Editor, Dr. Carolin Haug!
Palaeontologia Electronica (PE) would like to welcome its newest executive editor to the team, Dr. Carolin Haug! Dr. Haug has been part of the PE team since 2014, working as a handling editor. Please allow me to introduce Dr. Haug, her work, and her anticipations for this new role!