Nibbling prehistoric herbivore sheds new light on Triassic diversity
A Triassic herbivore, known for its supposed similarities to a modern-day ostrich, has been revealed to have entirely different approach to feeding from previously thought, according to research at the University of Birmingham.
The new discovery reveals a much broader diversity of herbivore behaviour during the Triassic period than has been recognised to date.
Called Effigia, the animal was about the size of a gazelle and lived in North America around 205 million years ago. Its fossil remains were found in the Ghost Ranch Quarry in New Mexico in the 1940s, although the material was not formally described by palaeontologists until 2006.
The remains had been relatively poorly preserved in the quarry and the skull, in particular, was quite badly deformed, making accurate reconstruction problematic. Early analysis of the specimen concluded that it belonged to the group of reptiles that includes crocodylians and birds and which started to flourish in the Triassic period.
Although more closely related to crocodylians, Effigia’s lightweight body, elongated neck, large eyes and beak shared many similarities with a modern-day ostrich, leading researchers to believe the animal fed by pecking plant material from the ground.
But new analysis of the specimen, by experts at the University of Birmingham, has revealed this animal was probably an entirely different type of herbivore than previously thought. The work, carried out in partnership with experts at the University of Bristol, University College London, University of York, Virginia Tech and the Natural History Museum, is published in The Anatomical Record.
The team used new CT scans of Effigia’s skull which revealed a much more accurate reconstruction of the animal. This included new information about the shape of the skull, such as a more rounded, bulbous brain cavity and curved upper and lower jaws. Unlike an ostrich bill, which is more rounded, Effigia’s bill is more concave with jaws that open and close a bit like a pair of shears.
The team used this information to model the effects of different forces acting on the skull, including what happens when the animal pecks at the ground. By modelling the forces the skull would need to withstand in order to feed by pecking, the researchers calculated that Effigia’s skull would probably have shattered. Instead, they suggest, the animal would be more likely to use its jaws to snip off and nibble pieces of soft plant material such as young shoots, or ferns.
Lead researcher, Dr Jordan Bestwick, said: “The herbivores we already recognise in the Triassic period fed either by digging for roots, such as the pig-like aetosaurs, or reaching for leaves high up in the treetops, like the long-necked sauropods. These two-legged browsers with a weak bite are unique to this period and show a previously unrecognised diversity among the herbivores of this period.”
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Journal Reference:
- Jordan Bestwick, Andrew S. Jones, Sterling J. Nesbitt, Stephan Lautenschlager, Emily J. Rayfield, Andrew R. Cuff, David J. Button, Paul M. Barrett, Laura B. Porro, Richard J. Butler. Cranial functional morphology of the pseudosuchian Effigia and implications for its ecological role in the Triassic. The Anatomical Record, 2021; DOI: 10.1002/ar.24827
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.”
Kyhytysuka video: https://www.youtube.com/watch?v=5URorvooZCQ
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Materials provided by McGill University. Note: Content may be edited for style and length.
Journal Reference:
- Dirley Cortés, Erin E. Maxwell, Hans C. E. Larsson. Re-appearance of hypercarnivore ichthyosaurs in the Cretaceous with differentiated dentition: revision of ‘Platypterygius’ sachicarum (Reptilia: Ichthyosauria, Ophthalmosauridae) from Colombia. Journal of Systematic Palaeontology, 2021; 1 DOI: 10.1080/14772019.2021.1989507
Tiny pterosaurs dominated Cretaceous skies
The babies of giant pterosaurs – known as flaplings – overshadowed their small adult rivals.
The newly hatched juveniles of large and gigantic pterosaurs likely outcompeted other smaller adult pterosaur species to dominate the Late Cretaceous period around 100 million years ago, a new study led by researchers from the University of Portsmouth has found.
Pterosaurs were the flying cousins of dinosaurs — some were as large as a Spitfire fighter plane and others as small as a thrush.
During the Triassic and Jurassic periods, 252 — 145 million years ago, pterosaurs reached only modest sizes, but by the Late Cretaceous period many were giants — some with a wingspan of 10 metres or more.
It had been previously thought that the smaller species of pterosaurs were outcompeted by newly evolving birds, but this research has found that it was actually the babies of giant pterosaurs — known as flaplings — who overshadowed their small adult rivals.
Lead author, Roy Smith, from the University of Portsmouth’s School of the Environment, Geography and Geosciences, worked on the study with scientists from Africa and the UK. The international team comprised of experts from the universities of Cape Town, Leicester, Portsmouth and Casablanca.
He said: “Over the last 10 years or so, we’ve been doing fieldwork in Morocco’s Sahara Desert and have discovered over 400 specimens of pterosaurs from the Kem Kem Group, highly fossiliferous sandstones famous worldwide for the spectacular dinosaur Spinosaurus.
“We’d found some really big pterosaur jaws and also specimens that looked like smaller jaws — about the size of a fingernail — but these tiny pterosaur remains could have just been the tips of big jaws so we had to do some rigorous testing to find out if they were from a small species or from tiny juveniles of large and giant pterosaurs.”
Roy and his colleagues examined five small jaw fragments and a neck vertebra using sophisticated microscope techniques to determine the age of the individual when the animal died.
Co-investigator, Anusuya Chinsamy-Turan, from the University of Cape Town in South Africa, is a world expert on the bone microstructure (histology) of pterosaurs and dinosaurs. She said: “By looking at the paper-thin section of the bones under a microscope, I could tell that they were from juveniles as the bone was fast growing and didn’t have many growth lines.
“We also examined the surface of the bones and found they had a rippled texture. This was further evidence they were the bones of immature individuals as mature pterosaur bones have an incredibly smooth surface once they are fully formed.”
The researchers also inspected the jaws and found that the number of tiny holes where nerves come to the surface for sensing their prey, known as ‘foramina’, were the same in the small jaws and the big jaws.
“This was more proof we were looking at the jaws of juveniles because if the specimens were just the tip of a jaw, there would be a fraction of the number of foramina,” said Roy.
Recent findings have suggested that hatchling pterosaurs could fly soon after hatching so they were quickly independent.
Professor David Martill of the University of Portsmouth said: “What really surprised me about this research is that the feeding ecology of these magnificent flying animals is more like that of crocodiles than of birds.
“With birds, there will be perhaps 10 different species of different sizes alongside a river bank — think kingfisher, little bittern, little egret, heron, goliath heron or stork for a large European river. There are several species all feeding on slightly different prey. This is called niche partitioning.
“Crocodiles on the other hand are much less diverse. On the river Nile, hatchling crocodiles feed on insects, and as they grow they change their diet to small fish, then larger fish and then small mammals, until a big adult Nile croc is capable of taking a zebra.
“There are lots of different feeding niches, but they are all occupied by one species at different stages of its life history. It seems that pterosaurs did something rather similar, occupying different niches as they grew — a much more reptilian rather than avian life strategy.
“It’s likely that the juvenile pterosaurs were feeding on small prey such as freshwater insects, tiny fishes and amphibians. As they grew they could take larger fishes — and who knows — the biggest pterosaurs might have been capable of eating small species of dinosaurs, or the young of large dinosaur species.”
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Materials provided by University of Portsmouth. Note: Content may be edited for style and length.
Journal Reference:
- Roy E. Smith, Anusuya Chinsamy, David M. Unwin, Nizar Ibrahim, Samir Zouhri, David M. Martill. Small, immature pterosaurs from the Cretaceous of Africa: implications for taphonomic bias and palaeocommunity structure in flying reptiles. Cretaceous Research, 2021; 105061 DOI: 10.1016/j.cretres.2021.105061