Fossils: 6 coolest techniques used in 2022 to reveal past mysteries
Yes, this article will include dinosaur fossils. After all, the extinct reptile group hardly fails when gripping attention, whether through the discovery of a new species or simply a new behavior. Movies like Jurassic Park and Kong: Skull Island (does the mutated therapod, Godzilla, count?) have further fueled our interest in these mysterious creatures. Yet, fossils from other types of animals do exist too - even hominin ones.
Here IE takes a more inclusive look. Through interviewing the scientists behind the work and shedding light, where applicable, on the technologies used to make these insights possible, let's walk through a selection of six fossil discoveries of 2022 so far.
1. The Annamite molar- a Denisovan girl in the tropics.
In May, the discovery of a young girl’s molar amongst other rare human remains in a limestone cave (Tam Ngu Hao 2) in the Annamite Mountains, Laos, was published in Nature. The molar, believed to belong to an extinct hominin species called Denisovan, has been estimated to be around 164,000 to 131,000 years old, based on a series of radioactive dating techniques of the rock it was recovered in and the surrounding geology.
“The discovery of a Denisovan under the tropics expands further to the South the territory of this species that was originally thought to only be adapted to cold regions as the first representatives were found in Siberia and on the Tibetan Plateau,” explains paleoanthropologist Fabrice Demeter of the University of Copenhagen's Lundbeck Foundation GeoGenetics Centre, lead author of the study. In other words, the presence of the Denisovan girl in continental Southeast Asia reveals a range not previously known for the species.
The research team was able to identify the gender by analyzing the ancient proteins in the internal structure of the molar- a method called palaeoproteomics. The close morphological affinities with an earlier discovered specimen in China- the Xiahe specimen- indicates that the two belong to the same taxon and help confirm that the Tam Ngu Hao 2 specimen is Denisovan.
2. The T-rex traded bigger eyes for a bigger bite
You’d think having tiny arms was enough for a T-rex regarding evolution’s questionable choice for stability. However, according to a study published in August in Nature, the famously ferocious predator also traded in smaller eyes for a more forceful bite. More specifically, theropod dinosaurs such as Allosaurus and Tyrannosaurus rex likely evolved different shaped eye sockets in order to withstand high bite forces better. So, maybe not that questionable after all.
The study used 410 fossilized reptile specimens from the Mesozoic period- which spans from 252 to 66 million years ago- to ultimately produce a computer-simulated bite.
“I found that the large carnivores had evolved these unusual eye socket shapes to mitigate stresses and deformation that would occur in the skull during feeding,” reveals Dr. Stephan Lautenschlager to IE, senior lecturer in Palaeobiology at the University of Birmingham and researcher who conducted the study. Such a bite would have been several times higher than that of a modern crocodile.
The research used two main methods; geometric morphometric analysis (GMM) and finite element analysis (FEA). GMM uses the same principle as face recognition, which is based on selecting a series of characteristic points as landmarks for identifying objects. The second, FEA, simulates how deformation and stress are distributed in an object when subjected to an external force. This technique has been used for decades in simulating car crashes but is relatively new in paleontology.
To the researcher’s surprise, the study, which included both adult and juvenile examples, revealed that the juvenile individuals always had a circular eye socket, even if the adult T-rex had keyhole-shaped eye sockets. This result suggests that high bite forces were not a priority for the juvenile, and by inference, they likely had a different diet and hunting strategy compared to a fully grown T. rex.
3. Mystery solved: The origins of warm-bloodedness in mammals
The ability of mammals to regulate their body temperature and generate their body heat is what makes them endothermic or warm-blooded. Yet, how this endothermy evolved in mammals' ancestors has been a long-standing problem in paleontology- until recently.
Results from a study published in July in Nature used a novel proxy, the inner ear, to pinpoint that warm-bloodedness in the mammalian lineage emerged rapidly, over a period of only around 1 million years, during the late Triassic period, about 233 million years ago. Before this research, it was thought that mammals emerged more slowly, over a period between 252 to 201 million years ago.
The researchers figured out that they could use shape changes in the three canals of the inner ear as precise guidance on when endotherms evolved. Like a bar of chocolate changes from solid to liquid when you melt it, or coconut oil thickens as it cools, the viscosity of ear canal fluid, or endolymph, changes with body temperature.
“Perhaps, the most surprising aspect of our research is that actually using the inner ear to estimate body temperature works! We know this because with have very high predictive accuracy (90 percent) when using our proxy in extant animals, which gives a lot of confidence for extinct animals,” explains D.r Ricardo Araújo to IE, lead author of the study.
Araújo and his colleagues first examined the inner ears of hundreds of modern animals. They found that the inner ear canals in mammals were more circular, smaller, and thinner relative to their body size compared to those in cold-blooded reptiles, amphibians, and fish.
The researchers also used state-of-the-art CT scanning techniques and 3D modeling to examine 56 extinct synapsid species from the Karoo region of South Africa- a group of fossils for which researchers have a great detail of information on their change from reptile-like animals to mammals.
Synchrotron radiation micro-tomography or typical X-ray micro-tomography- the same technology used in hospitals for imaging broken bones, was used to determine which species had inner ear anatomy corresponding to warmer body temperatures and which did not.
The results indicated that mammal ancestors first became warm-blooded over a roughly 1-million-year period during the late Triassic. This time frame also corresponds with the first known appearance of mammaliamorphs, mammalian ancestors that also had hairs and whiskers.
4. The combat scars of 'Big John'
Holes found in the iconic frill of the three-horned extinct reptile known as Triceratops have caused much debate in the paleontology community.
For the first time, a study published in April carried out a microscopic analysis of a traumatic frill injury on a Triceratops dubbed ‘Big John’ (Triceratops Horidus). The results suggest that the partially healed lesion was a result of fighting. Better yet, the size of the lesion coincides with that of a horn of an animal of similar size- i.e. potentially another Triceratops- with the location of the trauma suggesting that the blow was inflicted from behind.
The study also reveals that Big John probably survived for just a few months after the blow.
"The study confirms that the Triceratops not only had to defend themselves from predators but also had to fight [for] females or to defend their area. The results, therefore, add information on the behavior and habits of these huge dinosaurs," Dr. Ruggero D’Anastasio, lead author of the study, explains to IE.
The researchers made 30-micrometer-thick (1 micrometer is one-millionth of a meter) slices of the healing bone that delimited the lesion using a diamond-edged circular blade cutting tool known as a microtome. An electronic scanning field emission microscope fitted with a detector was used to capture the microstructure image of the ancient biological tissue. This setup meant that an advanced microanalysis of Big John could be carried out on the samples directly with no preliminary treatments with glues or surface preparation.
To the researcher’s surprise, the study also concluded that the cellular and molecular processes at work during the healing of Big John's trauma are very similar to those seen in mammals.
5. The mysterious 'sixth digit' of the giant panda
Did you know the living giant panda (Ailuropoda melanoleuca) has a ‘false thumb’ evolved specifically for grasping bamboo? That’s right, and it’s a sixth underdeveloped extra digit that forms an enlargement from an existing wrist bone known as the radial sesamoid. How such a primitive thumb evolved remained a mystery for more than 100 years- until recently.
In June, a paper published in Nature presented a fossil of a false thumb from an ancestral giant panda, Ailuractos. The six-seven million-year-old extinct panda from Yunnan, China, has shed some light on this evolutionary innovation. Unexpectedly, the ancestral panda’s false thumb is longer than the false thumb in its living relatives, despite the latter's longer time to evolve a more elaborate digit.
“We propose that the panda’s “thumb” performs a dual function of grasping bamboos and weight bearing. These two functions counterbalance each other, i.e., the weight-bearing function has apparently prevented the pandas from ever developing a full-fledged digit,” shares lead author Dr. Xiaoming Wang, curator and chairman at the department of Vertebrate Paleontology at the Natural History Museum of Los Angeles.
6. Europe’s largest predatory dinosaur- to date
In June, researchers from the University of Southampton published a study describing the discovery of a spinosaurid dinosaur, a potential new species that lived around 125 million years ago. While yet to receive a scientific name, the ‘White Rock spinosaurid,’ dubbed after the geological layer in which it was found, represents what is likely the largest predatory dinosaur from Europe known to date.
The new dinosaur supports previous suggestions that spinosaurids originated in western Europe before venturing into Asia, Africa, and South America.
“Some of the bones we have are massive, and it is likely the largest predatory dinosaur from Europe yet known, measuring over 10m and weighing several tonnes,” explains Ph.D. student Christopher Barker to IE, who led the study.
The remains found near Compton Chine on the southwest coast of the Isle of Wight include huge pelvic and tail vertebrae. Whilst dinosaur finds particularly in Cretaceous-aged rocks- i.e. between 145 and 66 million years old- are well known, the "White Rock spinosaurid" is a significant and unusual find as it comes from the bottom layer of a geological sequence known as the Vectis Formation- which is known to be poor in dinosaur fossils.
In a landscape of lagoonal waters and sandflats, it is envisaged that the huge two-legged crocodile-faced dinosaur would snap up fish and other dinosaurs, both on land and in water, with its meter-long, narrow snout. Is this a species you would have liked to have known in person?