̽��ֱ�� of Cambridge - Mammals

Species ‘hotspots’ created by immigrant influx or evolutionary speed depending on climate

fpjl2 — Wed, 06 Feb 2019 19:01:52 +0000

Some corners of the world teem with an extraordinary variety of life. Charles Darwin noted that: “ ̽��ֱ��same spot will support more life if occupied by very diverse forms.”

̽��ֱ��question of how these ‘hotspots’ of biodiversity – from California to the Galapagos – acquired such a wealth of species has long puzzled naturalists.

Now, scientists at the ̽��ֱ�� of Cambridge have conducted a ‘big data’ study of almost all the world’s mammal and bird species to reveal the answer – and it’s very different depending on climate.

According to the study, tropical hotspots close to the equator have generated new species at a much faster rate than their surrounding areas during the last 25 million years of evolution.

However, biodiversity hotspots in more temperate northerly regions, such as the Mediterranean basin and Caucasus Mountains, are mainly populated with immigrant species that originated elsewhere.

Scientists say these migrants may have been escaping the effects of long-term “geological processes” such as vast encroaching glaciers. Warmer climes, as well as peninsulas and mountain ranges, could have offered shelter.

̽��ֱ��researchers say that their new study, published today in the journal Science Advances, shows how these “contrasting macroevolutionary routes” have shaped the uneven distribution of species across the planet.

“We’ve known for decades that just a subset of places on Earth, no more than 20%, contain about half of all vertebrate species. However, we lacked the tools and data to understand why these patterns exist,” said senior author Dr Andrew Tanentzap, from Cambridge’s Department of Plant Sciences.

“Large-scale initiatives to map species across the planet and in the Tree of Life, as well as advances in computing, are expanding our understanding of evolution in exciting ways. This study can now provide an answer to the old question of why diversity varies so much across the world.”

Cambridge scientists used new computational techniques to combine several giant datasets. These included the global distribution of 11,093 bird species and 5,302 mammals, and detailed evolutionary trees that track the origin of thousands of organisms through deep time.

In this way, the researchers were able to analyse the development of particularly species-rich areas within each of the Earth’s great “biogeographical regions” – from Australasia to the Nearctic.

They found that biodiversity hotspots in the tropics, such as South American forests and Indonesian islands, had higher rates of “speciation” – the formation of new and distinct species – over the last 25 million years.

For example, speciation rates for birds in hotspots of the Indo-Malay region were, on average, 36% higher than that region’s non-hotspot areas. Hotspots in the Neotropics had almost 28% greater bird speciation compared to non-hotspots.

“Species generation is faster in the tropics, but we can now see it is extra-quick in these hotspots of biodiversity,” said study lead author Dr Javier Igea, also from Cambridge’s Department of Plant Sciences.

“More rainfall and hotter temperatures bolster the ecosystems of tropical hotspots, producing more plants, more animals that feed on those plants, and so on,” he said.

“ ̽��ֱ��greater available energy and range of habitats within these hotspots supported the acceleration of species diversification.”

̽��ֱ��tropical hotspot of Madagascar, for example, holds 12 species of true lemur that diversified in the last ten million years. All of the 17 species of earthworm mice endemic to the Philippines were generated in the last six million years.

̽��ֱ��famously diverse finches Darwin found in the Galapagos Islands, as featured in his revolutionary book On the Origin of Species, are an iconic example of rapid speciation in a tropical hotspot.

However, when it came to the more temperate regions of the Nearctic (North America) and Palearctic (Eurasia and North Africa), the researchers discovered a different story.

While the hotspots of these regions also had a wider range of resource and habitat than neighbouring areas, the data from the evolutionary – or phylogenetic – trees revealed that most of their animals “speciated” somewhere else.

“Biodiversity hotspots in temperate zones have been shaped mainly by migration that occurred during the last 25 million years,” said Igea.

“We suspect that this influx of immigrant species resulted from climate fluctuations across millions of years, particularly cooling. Biodiversity hotspots may have acted as a refuge where more species could survive in harsh climatic conditions,” he said.

Igea points to species such as the Iberian lynx, now a native of the Mediterranean Basin hotspot, but found in central Europe during the Pleistocene – prior to the last Ice Age.

Or the yellow-billed magpie, which became isolated in California after becoming separated from its ancestral species – most likely due to glaciations – over three million years ago.

“We found that hotspots across the world all have a greater complexity of habitats and more environmental energy, but the processes that drive the biodiversity are very different for tropical and temperate zones,” Igea said.

For Tanentzap, the importance of species migration in temperate regions suggests that maintaining connectivity between hotspots should be a priority for future conservation efforts.

“Many of these hotspot regions have species found nowhere else on Earth, yet face devastating levels of habitat loss. Protecting these areas is vital to conserving the natural world’s diversity,” he said.

Reference
Igea, J et al. Multiple macroevolutionary routes to becoming a biodiversity hotspot. Science Advances; 6 Feb 2019; DOI: 10.1126/sciadv.aau8067

A bold response to the world’s greatest challenge
̽��ֱ�� ̽��ֱ�� of Cambridge is building on its existing research and launching an ambitious new environment and climate change initiative. Cambridge Zero is not just about developing greener technologies. It will harness the full power of the ̽��ֱ��’s research and policy expertise, developing solutions that work for our lives, our society and our biosphere.

New research reveals that biodiversity ‘hotspots’ in the tropics produced new species at faster rates over the last 25 million years, but those in temperate regions are instead full of migrant species that likely sought refuge from shifting and cooling climates.

Many of these hotspot regions have species found nowhere else on Earth, yet face devastating levels of habitat loss

Andrew Tanentzap

Museum of Zoology / Chris Green

Galapagos finch specimens from Museum of Zoology, collected on the second voyage of HMS Beagle that carried Darwin to the Islands. Researchers say these famously diverse finches are an iconic example of rapid speciation in the tropics.

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. Images, including our videos, are Copyright © ̽��ֱ�� of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – as here, on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

Yes

Cooperation helps mammals survive in tough environments

fpjl2 — Tue, 24 Jan 2017 11:33:11 +0000

Cooperatively breeding mammal species, such as meerkats and naked-mole rats, where non-breeding helpers assist breeding females in raising their offspring, are better able to cope with living in dry areas than related non-cooperative species, new research reveals.

A comparative study of mammals, by ̽��ֱ�� of Cambridge researchers Dieter Lukas and Tim Clutton-Brock, shows that cooperatively breeding species occur in dry areas, yet are absent in tropical climates - even though these are the places on earth with the highest biodiversity.

Researchers have found that most cooperatively breeding mammals live in areas where it might not rain for weeks. While many have long argued that climate and social behaviour are linked, the Cambridge team say these findings provide a detailed understanding of how helping behaviour is connected to the environment individuals live in.

“Rainfall often affects food availability, and cooperatively breeding mammals appear better able to cope with the uncertainties of food availability during periods of drought,” said Lukas, from Cambridge’s Department of Zoology.

In this study, published in the journal Royal Society Open Science, the researchers mapped the global occurrence of mammalian species living in different social systems to determine how averages and variation in rainfall and temperature explain species distributions.

They found that although the presence of non-breeding adults in breeding groups is not associated with contrasts in climate, non-breeders commonly play an important role in raising the offspring of breeders in species living in dry environments.

“Long-term field studies show that helpers improve offspring survival, and our findings highlight that such cooperation is particularly important under harsh conditions,” said Clutton-Brock. Previous studies of birds show that here, too, non-breeding adults often help breeders to raise their young in species living in dry unpredictable environments.

Researchers say the activities of helpers in groups of cooperative mammals may ensure that infants and juveniles born in the group (who are usually closely related to them) are adequately fed, even when resources are scare.

In turn, non-breeders may gain future benefits from helping because it increases their chance that their group will survive adverse years, giving them a chance of inheriting the breeding position.

Groups of cooperative breeders occupy territories year-round. During droughts, mortality can be high, and only the largest groups might persist. “However, females in cooperatively breeding mammals can have very high rates of reproduction as soon as conditions are suitable. Populations can rebound, and dispersers move to fill vacant territories,” said Lukas.

By contrast, he says that many other mammals that live in arid areas are migratory, moving as resources are exhausted, such as the large ungulate herds roaming across the African savannahs.

Researchers say the new study also indicates that cooperation enables cooperative breeders to occupy a wider range of habitats than non-cooperative species which are limited to more favourable habitats.

Cooperative breeders are also twice as likely as non-cooperative mammals to occupy human-modified habitats suggesting that cooperative breeding may make it possible to colonize new environments. “Cooperative breeders may also persist in areas where changes in climate make life increasingly difficult,” said Clutton-Brock.

New research suggests that cooperative breeding makes mammal species such as meerkats better suited to dry, harsh climates.

Cooperative breeders may also persist in areas where changes in climate make life increasingly difficult

Tim Clutton-Brock

graham_alton

Meerkats

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Yes

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Attribution-Noncommercial-ShareAlike

Naked Mole-Rats: are these rodents immune to cancer?

amb206 — Wed, 02 Sep 2015 09:00:00 +0000

Scroll to the end of the article to listen to the podcast.

‘Bizarre’ is a kinder word than ‘ugly’ and may be a more accurate description when it comes to a rodent with remarkable attributes. ̽��ֱ��naked mole-rat might look a bit like a raw sausage with protruding teeth but its behaviour and physiology are fascinating.

Zoologists first began to explore the unusual lifestyle of the naked mole-rat in the 1970s, identifying it as the only known mammal to be ‘eusocial’. Rather like bees, naked mole-rats live in colonies in which powerful ‘queens’ control groups of as many as 300 animals.

Researchers soon discovered that this small animal, which is native to East Africa and lives exclusively underground, packs a number of other surprises. It is unique among mammals in being poikilothermic (cold blooded) and is extremely efficient in its use of resources.

When the naked mole-rat finds a calorie-packed underground tuber, it eats what it needs and then covers the tuber with soil so that it can continue growing, meaning that the naked mole-rat, like humans, farms its crops.

Now neuroscientists and others are focusing on the ways in which the naked mole-rat differs from other rodents (such as mice) in other unique respects as a means of understanding conditions such as ageing, cancer and pain.

Dr Ewan St. John Smith, a researcher in the Department of Pharmacology, is one of only two scientists in the UK to hold a Home Office licence that allows his group to keep and study naked mole-rats in laboratory conditions.

Naked mole-rats are not hard to keep – but they are difficult to breed successfully. Smith describes them as surprisingly endearing. “If you hold a mouse in the palm of your hand, it will often try to escape or pee on you! Naked mole-rats are really playful.”

Smith has been studying the naked mole-rat for the past ten years, moving from a broad interest in the animal’s peripheral sensory system (e.g. how the animals detect noxious stimuli) to focus on molecular and cellular mechanisms that enable healthy brain function throughout their long lives.

By understanding the physiology of the naked mole-rat, and its differences with that of mice, Smith and colleagues are helping to pinpoint mechanisms that might, in the future, help clinicians to treat human conditions.

Just one of the significant differences between naked mole-rats and other small rodents is their long and healthy life span: typically they live for 30 years against an average of two to three years for mice.

“Naked mole-rats age quickly right at the end of their lives – and the females remain fertile right to the end, sometimes producing as many as 20 offspring in a single litter,” said Smith.

An apparent resistance to the cancers which shorten the average lives of most mammals is likely to be a key reason for this longevity. “At this point in time, it might be an overstatement to suggest that naked mole-rats don’t get cancer,” says Smith.

“What we can say is that none of the animals examined in the course of autopsy studies in both zoos and research institutes has been shown to have a tumour. We can’t be completely sure they don’t develop cancer, but it’s certainly true that they are resistant to change on a cellular level.”

Another claim often made about naked mole-rats is that they don’t feel pain. Again, this is only partly true.

“Naked mole-rats do feel pain in response to stimuli such as heat and mechanical threats just as mice do,” says Smith. “But, unlike most other mammals, they do not react to acid-induced pain such as lemon juice, nor do they experience the burning sensation induced by capsaicin – the chemical found in chillies that produces their hotness.”

̽��ֱ��naked mole-rat’s resistance to acid-induced pain is thought to stem from its underground life style: the labyrinths of burrows in which colonies live are high in carbon dioxide and low in oxygen. Carbon dioxide produces acid when it mixes with bodily fluids and naked mole-rats have developed an insensitivity to acid-induced pain, which enables them to live in a habitat that to many other mammals would be toxic.

In a study published in 2011, Smith and colleagues discovered that the acid-insensitivity is likely to be the result of a variation in a protein that is responsible for sending electric signals in nerves from the periphery to the spinal cord. ̽��ֱ��naked mole-rat version of this protein is switched off by acid, which, like a local anaesthetic at the dentist, then prevents painful signals reaching the central nervous system.

“Identification of the differences between how the nervous system functions on a molecular level between species is the key to understanding more about the incredibly complex ways in which the human nervous system functions – and may, in the long term, help us to set targets for the development of new therapies for treatment of conditions such as chronic pain,” said Smith.

Next in the Cambridge Animal Alphabet: O is for a bird that is inspiring physicists to make wind turbines that are more efficient and less noisy.

Have you missed the series so far? Catch up on Medium here.

Inset images: Naked mole-rats (Ewan St. John Smith).

The Cambridge Animal Alphabet series celebrates Cambridge's connections with animals through literature, art, science and society. Here, N is for Naked Mole-Rats, which won't win any beauty contests, but can live for 30 years and may be able to help in the development of new therapies for chronic pain.

It’s certainly true that they are resistant to change on a cellular level

Ewan St. John Smith

Playful naked mole-rats

Ewan St. John Smith

Naked Mole-rat

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Yes

Females protect offspring from infanticide by forcing males to compete through sperm instead of violence

fpjl2 — Thu, 13 Nov 2014 19:08:52 +0000

Previous research has shown that infanticide by males is widespread in many mammal species, but most commonly occurs in those species where females live in social groups dominated by one or a few males.

Outsiders will fight dominant males for access to females. When a rival male takes over a group, they will kill the infants of previously dominant males to render the females ‘sexually receptive’ again, so that they can sire their own offspring. This may be the main cause of infant mortality in some species, such as Chacma baboons.

Now, a new study published today in the journal Science shows that these brutal acts are strategic; males may only have a short time in charge before they themselves are deposed, and want to ensure the maternal investment of females is directed towards their own future offspring for the longest time possible.

However, the females of some species - such as the mouse lemur - have evolved a highly-effective counter-strategy to stop males from killing their offspring: by having as many mates as possible in a short amount of time. By confusing the paternity of the infants, known as ‘paternity dilution’, any male act of infanticide risks the possibility of killing his own offspring.

In such species, reproductive competition shifts to after copulation, not before - so that the most successful male is the one whose sperm outcompetes those of the others. This leads to males producing ever larger quantities of sperm, leading in turn to increases in testis size. ̽��ֱ��testes of male mouse lemurs swell 5-10 times larger during the breeding season.

“In species in which infanticide occurs, testis size increases over generations, suggesting that females are more and more promiscuous to confuse paternity,” said lead author Dr Dieter Lukas, from ̽��ֱ�� of Cambridge’s Department of Zoology.

“Once sperm competition has become so intense that no male can be certain of his own paternity, infanticide disappears - since males face the risk of killing their own offspring, and might not get the benefit of siring the next offspring.”

Closely related species that differ in infanticide and testes size include chimpanzees (males commit infanticide) versus bonobos (males have not been observed to kill offspring). Bonobos have testes that are roughly 15% larger than those of chimpanzees.

Male Canadian Townsend voles don’t commit infanticide, and have 50% larger testes compared to infanticidal males of close relatives the North American meadow voles, says Lukas.

He conducted the research with colleague Dr Elise Huchard, who is now based at the CNRS Centre d’Ecologie Fonctionnelle et Evolutive in Montpellier.

Fifty years ago, observations of wild Hanuman langurs shattered previous depictions of monkey groups as peaceful, supportive societies, says Lukas, as new males that had just taken control of a group of females frequently killed all juveniles.

Subsequent observations have accumulated over the years on various mammals to show that infanticide by males is a widespread phenomenon, occurring in species from house mice to lions and gorillas. In some species, he says, the biggest risk faced by infants might not actually be predators or diseases, but the adult males of their own species.

In the latest study, Lukas and Huchard compiled and compared detailed field observations for 260 mammalian species to show that male infanticide occurs in species where sexual conflict is most intense, and reproduction is monopolised by a minority of males. ̽��ֱ��researchers’ findings indicate that infanticide is a manifestation of sexual conflict in mammalian social systems.

“While it had previously been suggested that infanticide might be an evolutionary driver in mammalian societies - leading to females allying themselves with other females or forming bonds with a specific male in order to defend their offspring - we’ve now shown that this isn’t the case: male infanticide is a consequence of variation in sociality, most commonly occurring in species where both sexes live together in stable groups,” said Lukas.

̽��ֱ��researchers say the new study supports the idea that infanticide isn’t a general trait present in all species, but is strategic and occurs only when it is advantageous to males. ̽��ֱ��study reveals the reversible nature of male infanticide, and that it is successfully prevented by the ‘paternity dilution’ strategy of female sexual promiscuity.

Added Huchard: “Male infanticide appears and disappears over evolutionary times according to the state of the evolutionary arms race between the sexes. Although infanticide may not have contributed to shape the diversity of mammalian social systems, it has deeply influenced the evolution of sexual behaviour and sex roles.

“This study also highlights that some of the greatest challenges faced by mammals during their lifetime come from others of their own species.”

Inset images: A male mouse lemur with large testes (credit: Cornelia Kraus). A Chacma baboon with dead infant (credit: Alice Baniel)

Latest research shows the females of some mammal species will have many mates to ensure unclear paternity, so that males can’t resort to killing their rival’s offspring for fear of killing their own. This forces males to evolve to compete through sperm quantity, leading to ever-larger testicles. Scientists find that as testis size increases, infanticide disappears.

Once sperm competition has become so intense that no male can be certain of his own paternity, infanticide disappears

Dieter Lukas

Elise Huchard

Baboon fight

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Yes

Monogamy evolved as a mating strategy

gm349 — Mon, 29 Jul 2013 19:00:02 +0000

Social monogamy, where one breeding female and one breeding male are closely associated with each other over several breeding seasons, appears to have evolved as a mating strategy, new research reveals. It was previously suspected that social monogamy resulted from a need for extra parental care by the father.

̽��ֱ��comparative study, by ̽��ֱ�� of Cambridge researchers Dieter Lukas and Tim Clutton-Brock, shows that the ancestral system for all mammalian groups is of females living in separate ranges with males defending overlapping territories, and that monogamy evolved where males were unable to monopolise and defend multiple females. ̽��ֱ��research is published in the journal Science.

For the study, the researchers classified all 2500 mammalian species for which information exists as either solitary, socially monogamous or group-living (several breeding females share a common range and either eat or sleep together). They showed that nine per cent of mammals are socially monogamous, including a few rodents, a number of primates, and some carnivores, like jackals, wolves, and meerkats.

Previously, it had been suggested that monogamy evolved as a result of selection for paternal support in raising offspring (for example, if the female alone could not provide enough food or adequately defend the young). This study shows that paternal care usually evolved after monogamy was already present.

This advance in understanding was, says Lukas of Cambridge's Department of Zoology, due to the volume of information they collected and the availability of genetic information that allowed the researchers to determine the sequence in which different traits evolved.

"Up until now, there have been different ideas about how social monogamy in mammals evolved," says Lukas. "With this study we were able to test all these different hypotheses at once. Paternal care evolves after monogamy is present, and seems to be a consequence rather than a cause of the evolution of monogamy. It appears to occur in about half of all socially monogamous species, and once it does evolve, it provides a clear benefit to the female."

They found convincing support for the hypothesis that monogamy arose as a mating strategy where males could not defend access to more than one female. Monogamy is associated with low density of females, low levels of home-range overlap, and indirectly, with their diets. ̽��ֱ��study showed that monogamy evolves in species that rely on high quality but patchily distributed food sources, such as meat and fruit. In contrast, in herbivores, which rely on more abundant resources, social monogamy is rare.

"Where females are widely dispersed," says Clutton-Brock, "the best strategy for a male is to stick with one female, defend her, and make sure that he sires all her offspring. In short, a male's best strategy is to be monogamous."

̽��ֱ��analysis did not include humans, and the researchers are sceptical that these results tell us much about the evolution of human breeding systems.

Clutton-Brock adds: "It is debatable whether humans should be classified as monogamous. Because all the African apes are polygamous and group living, it is likely that the common ancestor of hominids was also polygamous. One possibility is that the shift to monogamy in humans may be the result in the change of dietary patterns that reduce female density, and another is that slow development of juveniles required extended care by both sexes. However, reliance by humans on cultural adaptations means that it is difficult to extrapolate from ecological relationships in other animals."

For more information about this story, please contact: Genevieve Maul, Office of Communications, ̽��ֱ�� of Cambridge. Email: Genevieve.Maul@admin.cam.ac.uk; Tel: 01223 765542.

New research indicates that social monogamy evolved as a result of competition for females.

Where females are widely dispersed, the best strategy for a male is to stick with one female, defend her, and make sure that he sires all her offspring. In short, a male's best strategy is to be monogamous.

Professor Tim Clutton-Brock

Peter Brotherton

̽��ֱ��socially monogamous dik-dik, a small antelope that lives in Africa.

This work is licensed under a Creative Commons Licence. If you use this content on your site please link back to this page.

Yes

Mammals vs dinosaurs

tdk25 — Fri, 15 Mar 2013 09:23:04 +0000

Dinosaurs, as every schoolchild knows, were not just the most terrifying creatures ever to roam the Earth, but also the most exciting, and therefore the best. ̽��ֱ��peak of their golden age was one in which monstrous reptiles and carnivorous predators stalked the planet. True, not all of them were as big as houses, but some could grow up to 150 feet in length and more than 30 feet high. And the fiercest of the lot had no equal. Megaraptors, for example, possessed huge, sickle-like claws and powerful jaws with serrated teeth. Utahraptors, some palaeontologists have speculated, could run at speeds exceeding 50mph as they hunted down their prey in order to satiate their taste for flesh.

No wonder, then, that dinosaurs have been captivating the public for generations - ever since the Victorian age, in fact, when palaeontology really began to flourish as a science. Mammals, on the other hand, have always seemed a bit tame by comparison. In fairness, the biological class Mammalia makes some pretty decent contributions to the prehistoric record - think of the woolly mammoth, for example, or Smilodon (one of the many sabre-toothed tigers). In the final analysis, though, nobody ever made a film based on a book called “Pliocene Park”, nor a board game called “Lost Valley of the Marsupials”. Viewing figures for a TV series entitled “When Mammals Roamed America” would probably have left advertisers bitterly disappointed.

Yet while dinosaurs continue to thrill and intrigue us, Cambridge zoologist Nick Crumpton reckons that other prehistoric animals have been getting a raw deal. He argues that there are plenty such creatures that existed before, during and after the dinosaur age, and which, far from less interesting, are simply less well-known. In practice, they were – if not better – than certainly brainier, stealthier, and more capable of surviving in a wide range of different environments, than their dino counterparts.

In recent years, scientists have uncovered much more about these often overlooked specimens. Thanks to their efforts, there has never been a better moment to set the record straight in the contest between dinosaurs and other animals for our hearts and minds, and the time is ripe for the likes of the Phytosaur, Lycaenops, or even the humble Morganucodon to step out from the dinosaurs’ substantial shadows and claim their rightful place in public awareness. This Saturday (March 16), Crumpton will be on a mission to achieve exactly that at the Cambridge Science Festival. Not wishing to show bias towards either side in this epic clash of prehistoric heavyweights, his talk bears the modest and subdued title: “DINOBORES: Why mammals are way cool”.

“It’s a real shame that everyone knows about these incredible dinosaurs which evolved and ruled the Earth until 65 million years ago, but less about the amazing animals that in some cases predated them,” Crumpton says.

̽��ֱ��idea for the talk came to him while he was co-authoring a children’s book, “Triassic Terrors”, which is being published by Flying Eye Books. “As we were writing it I realised that the most fun bits to write weren’t about dinosaurs, because during the Triassic period - about 200 million years ago - dinosaurs were really just evolving. There were, however, incredible mammals that we don’t hear of. ̽��ֱ��same is true of periods when dinosaurs really thrived, the Jurassic and Cretaceous. And that’s a pity, because some of the most important fossils for such mammals have been found right here in the British Isles.”

In truth, Crumpton’s interest lies not just with mammals, but with a whole host of animals which have traditionally barely been recognised because of the more established and charismatic appeal of the dinosaurs. Recent finds and thorough research, however, are allowing scientists to change that picture, and they are beginning to realise that the world hundreds of millions of years ago was populated by a far greater diversity of life than had previously been imagined.

This applies to prehistory before dinosaurs as well as during the dinosaur age. In the Permian period, for example (roughly 298 to 252 million years ago), we have evidence of animals such as Gorgonopsids - large, carnivorous, four-legged monsters with long, sabre-like fangs, strong rear legs, and a vaulted palate that allowed them to breathe when they grabbed their prey. ̽��ֱ��biggest was roughly the size of a large bear.

One of the best-known is Gorgonops itself, the dominant predator of its day, which thanks to its pillar-like rear legs probably moved at very fast speeds. Another, called Lycaenops, had powerful canine teeth in both its upper and lower jaws, which meant that despite measuring about three feet in size, it was capable of stabbing or tearing at much larger animals - although it probably stuck to hunting reptiles and other small prey most of the time. Its leg positioning was such that it was probably much more agile than many contemporary creatures, and able to outrun them to hunt them down.

Mammals are not the only interesting, but little-known creatures from around this time for which fossil evidence is growing. Today, for example, we are familiar with crocodiles and alligators, which are reptiles. Yet these are just two surviving examples of a much larger lineage called Pseudosuchia, which thrived during Triassic times, and in some cases were a much more fearsome prospect.

Take, for example, Ornithosuchus (literally “bird crocodile”), which was a sufficiently terrifying flesh-eater that for some time palaeontologists believed it was actually an ancestor to T-Rex. In fact, it wasn’t a dinosaur at all, and probably resembled a crocodile in looks to some extent, although worryingly it could stand on two legs when it needed to. It was also bigger – probably about four metres (13 feet) in length. Not something you want to run into, nor indeed away from, given that it could probably move pretty swiftly, as well.

̽��ֱ��preeminence of dinosaurs really only began about 200 million years ago, when there was a sudden, devastating extinction event which probably wiped out something like half of the life on Earth. Until then, dinosaurs had only really had a bit-part in natural history, but thanks to “a quirk of fate”, as Crumpton puts it, their line recovered faster than most others, and so began the golden age of dinosaurs.

This, however, did not rule out the existence of mammals. For example, scientists have uncovered the remains of a small, squirrel-sized mammal that lived at least 125 million years ago, at a time when dinosaurs were dominant. This appears to have had a sizable, furry “patagium” - an extension of its skin, a bit like bat wings, and similar to that seen in flying squirrels today. Whatever this creature was, it was clearly gliding around the place in exactly the same age as the reptilian Pterosaurs.

Morganucodon, also a contemporary of dinosaurs, was an apparently less-spectacular, nocturnal creature. It lived about 205 million years ago and many remains attesting to its existence have been found in Glamorgan, in Wales. This small, furry animal had quite a long tail and a skull two to three centimetres in length, lived in a burrow, and might have looked a bit like a vole. It survived by eating insects, and other small animals.

As face-offs go, this appears to be something of a no-brainer. On the one hand, Megaraptors were large, terrifying and had big claws and pointy teeth. On the other, the likes of Morganucodon were certainly furry, possibly cute, and spent their day in a hole refusing to go outside.

Crumpton, however, argues that looks aren’t everything. “For some reason, people seem to have latched on to the idea of dinosaurs. But non-avian dinosaurs had small brains relative to their body-size, senses which weren’t as well developed, didn’t have endothermy as we do, and probably weren’t as good at parenting,” he complains. More constructively, he also points out that it was precisely the capacity of mammals to better these shortcomings which meant that, when the dinosaurs themselves were wiped out by another extinction event, probably caused by an asteroid hitting the Yucatan Peninsula 65 million years ago, mammals were able to fill the ecological niche they had left behind.

Once this happened, the mammals “really went to town”. Whales evolved where no fully aquatic dinosaurs had existed. Bats became so successful that today there are over 1,000 different species of bat on Earth. It wasn’t just the dinosaurs’ ecological niche that was occupied - everything was up for grabs.

So what was it that made mammals so successful, once they were given this chance to capitalise on the dinosaurs’ extinction? One significant asset was their relatively large brain size. “Bigger brains basically means better senses,” Crumpton explains. “Morganucodon was able to scamper around at night because it had better senses for coping in a nocturnal environment. Some of these animals also probably had a better sense of balance, which helped the flying squirrel-like creatures to glide through the air. Later these senses would enable them to communicate with each other, or co-ordinate hunts, like wolves. It’s highly unlikely, judging by the size of its brain, whether a T. Rex could have managed that.”

Then there was the fact that they were endothermic, or warm-blooded. Although there is some evidence for endothermy in a few groups of dinosaurs, the widespread warm-bloodedness found in mammals led to a range of physiological advantages. In particular, mammals had an increased metabolic rate and more energy available “on demand”, which meant that they could withstand temperature changes in a manner that dinosaurs could not. Nearly all reptiles today still bask on rocks in order to warm up in the sunshine. Mammals did not need to do this, and were far less vulnerable as a result.

As well as remarkable because they seem half-forgotten and exotic, Crumpton argues that prehistoric mammals and other animals were also amazing because they had qualities and capabilities that dinosaurs lacked. “I still love dinosaurs - they were what got me into biology when I was a kid and I don’t mean to resurrect an incorrect Victorian image of lumbering monsters dragging themselves slowly around the Earth,” he insists. “But now that I know more about life on Earth, it feels like it’s time to pay more attention to all these other incredible creatures that lived before the time of the dinosaurs, during it, and after they were gone.”

Nick Crumpton will be giving his free talk, “Dinobores: Why mammals are way cool”, on Saturday 16 March, from 10 - 10.45am in Arts School Room A on the New Museums Site, Pembroke Street, Cambridge. ̽��ֱ��event is one of a huge range of activities for all ages that are being organised for “Science On Saturday”, part of the Cambridge Science Festival.

Were dinosaurs really the most exciting and interesting creatures ever to roam the planet? Zoologist Nick Crumpton tells the Cambridge Science Festival that it’s high time other prehistoric animals stepped out from the shadows.

It’s time to pay more attention to all the other incredible creatures that lived before the time of the dinosaurs, during it, and after they were gone.

Nick Crumpton

Jordan Mallon / Sergiodlarosa

Megaraptor vs Smilodon.

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