Early mammals lived longer

What distinguishes the growth and development patterns of early mammals of the Jurassic period? This is the question jointly investigated by researchers of Queen Mary University of London and the University of Bonn. Paleontologists have been able to gauge the lifespan and growth rates of these ancient animals, and even when they reached sexual maturity, by studying growth rings in fossilized tooth roots. The study has now been published in the journal Science Advances.

"Never before have we been able to reconstruct the growth patterns of these early mammals in such detail," says lead author Dr. Elis Newham, a postdoc at Queen Mary University of London who during the study was an Alexander von Humboldt Research Fellow at the University of Bonn, up to March 31, 2024.

For the study, the team analyzed fossilized tooth roots of mammal species from the Early to Late Jurassic periods (200-150 million years ago) found at three separate sites. The finds made in Wales are of some of the oldest known mammalian precursors from the Early Jurassic period, while the fossils found in Oxfordshire, UK are of a very broad array of coexisting early mammals. The fossils from the third site in Portugal date from the Late Jurassic.

Fossil tooth roots X-rayed

The research team studied the fossils using a technique called synchrotron X-ray tomography in which electrons are accelerated to near light speed (unlike regular X-ray imaging). The technique affords several advantages, starting with the fact that the fossils no longer have to be prepared, i.e. cut up into slices, so they can be analyzed whole. Furthermore, images obtained via synchrotron X-ray tomography are of higher quality than images from conventional X-ray microtomography.

Researchers were able to image tiny growth rings in fossilized root cement -- the bone tissue that attaches the teeth to the jaw. "The rings are similar to those in trees, but on a microscopic level," explains Professor Thomas Martin of the Vertebrates -- Mammals working group at the University of Bonn Institute of Organismic Biology, who is a senior author of the study. "Counting the rings and analyzing their thickness and texture enabled us to reconstruct the growth patterns and lifespans of these extinct animals."

The researchers determined that the first signs of the growth patterns characteristic of modern mammals, such as a puberty growth spurt, started emerging roughly 150 million years ago. Early mammals grew much more slowly but lived substantially longer than today's small mammals, with lifespans of eight to fourteen years instead of just one or two as in modern mice, for example. However, it took early mammals years to reach sexual maturity, again in contrast to their modern descendants which reach sexual maturity in just a few months.

"Our findings suggest that the distinctive life history patterns of mammals, characterized by high metabolic rates and extended parental care phases for example, have evolved over millions of years," Dr. Elis Newham explains, "The Jurassic period appears to have been a crucial time for this shift."

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AI provides more accurate analysis of prehistoric and modern animals, painting picture of ancient world

A new Rice University study of the remains of prehistoric and modern African antelopes found that AI technology accurately identified animals more than 90% of the time compared to humans, who had much lower accuracy rates depending on the expert.

Composite images of teeth from five different antelope tribes analyzed and identified by artificial intelligence.

Photo courtesy of Manuel Domínguez-Rodrigo.

Identifying these animals and their habits helps paint a broader picture of ancient ecosystems, and with the assistance of this new technology, it can be done with more speed and accuracy than previously done by paleontologists, according to the study.

"African bovid tribe classification using transfer learning and computer vision" appeared in a recent edition of Annals of the New York Academy of Sciences.

The study outlines the groundbreaking AI technology used to analyze prehistoric livestock remains.

So why does it matter how these ancient animals lived and what they ate?

According to Manuel Domínguez-Rodrigo, visiting professor of anthropology at Rice, co-director of Madrid's Institute of Evolution in Africa and professor of prehistory at the University of Alcalá in Spain, the study sheds light on how the ecology of the time affected the evolution of mammal communities including humans, who over the past two million years have become highly dependent on other mammals.

"The evolution of ecosystems in Africa is of major relevance to understand what shaped our own evolution as humans," Domínguez-Rodrigo said.

"Our prehistoric ancestors were highly dependent on resources available in different habitats of African savanna ecosystems. Using fossil mammals -- highly specialized in their adaptations to different habitats -- to reconstruct these landscapes has been the most used method to interpret their ecology. Identifying those mammals by their teeth has not always been straightforward and was subjected to a high degree of expert knowledge and bias. Now we can do that with much more confidence. This will enable us to understand past environments but also understand better modern landscapes too when documenting the dead animals that they still contain."

And thanks to this technology, whose application to paleobiology is pioneered in Domínguez-Rodrigo's lab, he says archaeologists can now analyze information far more quickly and accurately than before.

"These AI methods are a revolution for the studies of paleobiology and human evolution in particular," he said.

"They provide an objective, replicable way of identifying animals, including the degree of confidence with which identifications are made."

Domínguez-Rodrigo said the success of AI in other fields, such as image-based medicine, was a proof of concept for its widespread application to other fields.

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Ancient sea monster remains reveal oldest mega-predatory pliosaur

The fossils of a 170-million-year-old ancient marine reptile from the Age of Dinosaurs have been identified as the oldest-known mega-predatory pliosaur -- a group of ocean-dwelling reptiles closely related to the famous long-necked plesiosaurs. The findings are rare and add new knowledge to the evolution of plesiosaurs. The study has been published in the journal Scientific Reports.

The fossils were found 40 years ago in north-eastern France. An international team of palaeontologists from the Naturkunde-Museum Bielefeld in Germany, the Institute of Paleobiology of the Polish Academy of Sciences in Warsaw, Poland, the Natural History Museum in Luxembourg and The Museum of Evolution at Uppsala University in Sweden have now analysed them and identified them as a new pliosaur genus: Lorrainosaurus.

Pliosaurs were a type of plesiosaur with short necks and massive skulls. They appeared over 200 million years ago, but remained minor components of marine ecosystems until suddenly developing into enormous apex predators. The new study shows that this adaptive shift followed feeding niche differentiation and the global decline of other predatory marine reptiles over 170 million years ago.

Lorrainosaurus is the oldest large-bodied pliosaur represented by an associated skeleton. It had jaws over 1.3 m long with large conical teeth and a bulky 'torpedo-shaped' body propelled by four flipper-like limbs.

"Lorrainosaurus was one of the first truly huge pliosaurs. It gave rise to a dynasty of marine reptile mega-predators that ruled the oceans for around 80 million years," explains Sven Sachs, a researcher at the Naturkunde-Museum Bielefeld, who led the study.

This giant reptile probably reached over 6 m from snout to tail, and lived during the early Middle Jurassic period. Intriguingly, very little is known about plesiosaurs from that time.

"Our identification of Lorrainosaurus as one of the earliest mega-predatory pliosaurs demonstrates that these creatures emerged immediately after a landmark restructuring of marine predator ecosystems across the Early-to-Middle Jurassic boundary, some 175 to 171 million years ago. This event profoundly affected many marine reptile groups and brought mega-predatory pliosaurids to dominance over 'fish-like' ichthyosaurs, ancient marine crocodile relatives, and other large-bodied predatory plesiosaurs," adds Daniel Madzia from the Institute of Paleobiology of the Polish Academy of Sciences, who co-led the study.

Pliosaurs were some of the most successful marine predators of their time.

"Famous examples, such as Pliosaurus and Kronosaurus -- some of the world's largest pliosaurs -- were absolutely enormous with body-lengths exceeding 10 m. They were ecological equivalents of today's Killer whales and would have eaten a range of prey including squid-like cephalopods, large fish and other marine reptiles. These have all been found as preserved gut contents," said senior co-author Benjamin Kear, Curator of Vertebrate Palaeontology and Researcher in Palaeontology at The Museum of Evolution, Uppsala University.

The recovered bones and teeth of Lorrainosaurus represent remnants of what was once a complete skeleton that decomposed and was dispersed across the ancient sea floor by currents and scavengers.

"The remains were unearthed in 1983 from a road cutting near Metz in Lorraine, north-eastern France. Palaeontology enthusiasts from the Association minéralogique et paléontologique d'Hayange et des environs recognised the significance of their discovery and donated the fossils to the Natural History Museum in Luxembourg," said co-author Ben Thuy, Curator at the Natural History Museum in Luxembourg.

Other than a brief report published in 1994, the fossils of Lorrainosaurus remained obscure until this new study re-evaluated the finds. Lorrainosaurus indicates that the reign of gigantic mega-predatory pliosaurs must have commenced earlier than previously thought, and was locally responsive to major ecological changes affecting marine environments covering what is now western Europe during the early Middle Jurassic.

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Oldest known species of swimming jellyfish identified

Royal Ontario Museum (ROM) announces the oldest swimming jellyfish in the fossil record with the newly named Burgessomedusa phasmiformis. These findings are announced in the journal Proceedings of the Royal Society B.

Jellyfish belong to medusozoans, or animals producing medusae, and include today's box jellies, hydroids, stalked jellyfish and true jellyfish. Medusozoans are part of one of the oldest groups of animals to have existed, called Cnidaria, a group which also includes corals and sea anemones. Burgessomedusa unambiguously shows that large, swimming jellyfish with a typical saucer or bell-shaped body had already evolved more than 500 million years ago.

Burgessomedusa fossils are exceptionally well preserved at the Burgess Shale considering jellyfish are roughly 95% composed of water. ROM holds close to two hundred specimens from which remarkable details of internal anatomy and tentacles can be observed, with some specimens reaching more than 20 centimetres in length. These details enable classifying Burgessomedusa as amedusozoan. By comparison with modern jellyfish, Burgessomedusa would also have been capable of free-swimming and the presence of tentacles would have enabled capturing sizeable prey.

"Although jellyfish and their relatives are thought to be one of the earliest animal groups to have evolved, they have been remarkably hard to pin down in the Cambrian fossil record. This discovery leaves no doubt they were swimming about at that time," said co-author Joe Moysiuk, a Ph.D. candidate in Ecology & Evolutionary Biology at the University of Toronto, who is based at ROM.

This study, identifying Burgessomedusa, is based on fossil specimens discovered at the Burgess Shale and mostly found in the late 1980s and 1990s under former ROM Curator of Invertebrate Palaeontology Desmond Collins. They show that the Cambrian food chain was far more complex than previously thought, and that predation was not limited to large swimming arthropods like Anomalocaris (see field image showing Burgessomedusa and Anomalocaris preserved on the same rock surface).

"Finding such incredibly delicate animals preserved in rock layers on top of these mountains is such a wonderous discovery. Burgessomedusa adds to the complexity of Cambrian foodwebs, and like Anomalocaris which lived in the same environment, these jellyfish were efficient swimming predators," said co-author, Dr. Jean-Bernard Caron, ROM's Richard Ivey Curator of Invertebrate Palaeontology. "This adds yet another remarkable lineage of animals that the Burgess Shale has preserved chronicling the evolution of life on Earth."

Cnidarians have complex life cycles with one or two body forms, a vase-shaped body, called a polyp, and in medusozoans, a bell or saucer-shaped body, called a medusa or jellyfish, which can be free-swimming or not. While fossilized polyps are known in ca. 560-million-year-old rocks, the origin of the free-swimming medusa or jellyfish is not well understood. Fossils of any type of jellyfish are extremely rare. As a consequence, their evolutionary history is based on microscopic fossilized larval stages and the results of molecular studies from living species (modelling of divergence times of DNA sequences). Though some fossils of comb-jellies have also been found at the Burgess Shale and in other Cambrian deposits, and may superficially resemble medusozoan jellyfish from the phylum Cnidaria, comb-jellies are actually from a quite separate phylum of animals called Ctenophora. Previous reports of Cambrian swimming jellyfish are reinterpreted as ctenophores.

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Extinct swordfish-shaped marine reptile discovered

A team of international researchers from Canada, Colombia, and Germany has discovered a new marine reptile. The specimen, a stunningly preserved metre-long skull, is one of the last surviving ichthyosaurs -- ancient animals that look eerily like living swordfish.

"This animal evolved a unique dentition that allowed it to eat large prey," says Hans Larsson, Director of the Redpath Museum at McGill University. "Whereas other ichthyosaurs had small, equally sized teeth for feeding on small prey, this new species modified its tooth sizes and spacing to build an arsenal of teeth for dispatching large prey, like big fishes and other marine reptiles."

"We decided to name it Kyhytysuka which translates to 'the one that cuts with something sharp' in an indigenous language from the region in central Colombia where the fossil was found, to honour the ancient Muisca culture that existed there for millennia," says Dirley Cortes, a graduate student under the supervision of Hans Larsson and Carlos Jaramillo of the Smithsonian Tropical Research Institute.

The big picture of ichthyosaur evolution is clarified with this new species, the researchers say. "We compared this animal to other Jurassic and Cretaceous ichthyosaurs and were able to define a new type of ichthyosaurs," says Erin Maxwell of the State Natural History Museum of Stuttgart (a former graduate student of Hans Larsson's lab at McGill). "This shakes up the evolutionary tree of ichthyosaurs and lets us test new ideas of how they evolved."

According to the researchers, this species comes from an important transitional time during the Early Cretaceous period. At this time, the Earth was coming out of a relatively cool period, had rising sea levels, and the supercontinent Pangea was splitting into northern and southern landmasses. There was also a global extinction event at the end of the Jurassic that changed marine and terrestrial ecosystems. "Many classic Jurassic marine ecosystems of deep-water feeding ichthyosaurs, short-necked plesiosaurs, and marine-adapted crocodiles were succeeded by new lineages of long-necked plesiosaurs, sea turtles, large marine lizards called mosasaurs, and now this monster ichthyosaur" says Dirley Cortes.

"We are discovering many new species in the rocks this new ichthyosaur comes from. We are testing the idea that this region and time in Colombia was an ancient biodiversity hotspot and are using the fossils to better understand the evolution of marine ecosystems during this transitional time," she adds. As next steps the researchers are continuing to explore the wealth of new fossils housed in the Centro de Investigaciones Paleontológicas of Villa de Leyva in Colombia. "This is where I grew up," says Cortes "and it is so rewarding to get to do research here too."

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