Early Mammals Acted More Like Reptiles, Says Study

KEY POINTS

  • Scientists said early mammals led a less active but much longer lives
  • They analyzed teeth fossils of earliest mammals, the Morganucodon and Kuehneotherium
  • The study suggested that mammals developed some characteristics like warm-bloodedness at a later period

The first mammals that roamed the Earth millions of years ago functioned and acted more like reptiles even with their already advanced body structures, a new study showed. 

The research, published in Nature Communications, suggested there might be an overlap between warm-bloodedness and cold-bloodedness as mammals evolved in the past. It may be noted that mammals are considered as warm-blooded animals while reptiles are cold-blooded. 

As part of the study, a team of paleontologists analyzed teeth fossils from two of the earliest mammals, the Morganucodon and Kuehneotherium, which lived alongside early dinosaurs nearly 200 million years ago. This was the first time researchers used powerful X-rays to examine ancient fossils.

The

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Ancient tiny teeth reveal first mammals lived more like reptiles — ScienceDaily

Pioneering analysis of 200 million-year-old teeth belonging to the earliest mammals suggests they functioned like their cold-blooded counterparts — reptiles, leading less active but much longer lives.

The research, led by the University of Bristol, UK and University of Helsinki, Finland, published today in Nature Communications, is the first time palaeontologists have been able to study the physiologies of early fossil mammals directly, and turns on its head what was previously believed about our earliest ancestors.

Fossils of teeth, the size of a pinhead, from two of the earliest mammals, Morganucodon and Kuehneotherium, were scanned for the first time using powerful X-rays, shedding new light on the lifespan and evolution of these small mammals, which roamed the earth alongside early dinosaurs and were believed to be warm-blooded by many scientists. This allowed the team to study growth rings in their tooth sockets, deposited every year like tree rings, which

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Nearly Half of South America’s Mammals Came from North America, New Research May Explain Why | Smart News

North and South America haven’t always been connected. South America functioned as a continent-sized island for millions of years following the extinction of the dinosaurs, incubating its own strange assembly of animals such as giant ground sloths, massive armored mammals akin to armadillos and saber-toothed marsupial carnivores. Meanwhile, North America was exchanging animals with Asia, populating it with the ancestors of modern horses, camels and cats, writes Asher Elbein for the New York Times.

Finally, when tectonic activity formed the Isthmus of Panama roughly ten million years ago, a massive biological exchange took place. The many species that had been evolving in isolation from one another on both continents began migrating across the narrow new land bridge. Llamas, raccoons, wolves and bears trekked south, while armadillos, possums and porcupines went north.

It would be reasonable to expect this grand biological and geological event, known to paleontologists as the Great

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Double jeopardy for ecologically rare birds and terrestrial mammals

endangered species
Credit: Pixabay/CC0 Public Domain

Common assumptions notwithstanding, rare species can play unique and essential ecological roles. After studying two databases that together cover all known terrestrial mammals and birds worldwide, scientists from the CNRS, the Foundation for Biodiversity Research (FRB), Université Grenoble Alpes, and the University of Montpellier have demonstrated that, though these species are found on all continents, they are more threatened by human pressures than ecologically common species and will also be more impacted by future climate change. Thus, they are in double jeopardy. The researchers’ findings, published in Nature Communications (October 8, 2020), show that conservation programs must account for the ecological rarity of species.


It has long been thought that rare species contribute little to the functioning of ecosystems. Yet recent studies have discredited that idea: Rarity is a matter not only of the abundance or geographical range of a species, but also of the distinctiveness

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Double jeopardy for ecologically rare birds and terrestrial mammals — ScienceDaily

Common assumptions notwithstanding, rare species can play unique and essential ecological roles. After studying two databases that together cover all known terrestrial mammals and birds worldwide, scientists from the CNRS, the Foundation for Biodiversity Research (FRB), Université Grenoble Alpes, and the University of Montpellier[1] have demonstrated that, though these species are found on all continents, they are more threatened by human pressures than ecologically common species and will also be more impacted by future climate change. Thus they are in double jeopardy. The researchers’ findings, published in Nature Communications (October 8, 2020), show that conservation programmes must account for the ecological rarity of species.

It has long been thought that rare species contribute little to the functioning of ecosystems. Yet recent studies have discredited that idea: rarity is a matter not only of the abundance or geographical range of a species, but also of the distinctiveness of its ecological functions.

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