How Placental Mammals, Like Whales and Humans, Evolved Bigger Brains and an Evolutionary Advantage

The main dishes to remember on placental mammals

• The placental mammals have a placenta, an organ that develops during gestation and folds the mother and the fetus.

• The placenta provides nutrients to the fetus to develop in the uterus, protecting the baby from the outside world until they are fully developed.

• Although we did not know the first placental mammal certainly because of their low preservation potential, we know that around 55 million years ago, 10 million years after the extinction of dinosaurs, the placental mammals exploded in number while the marsupials decreased.

Placental mammals guessed it, a placentaThe important organ that develops during gestation and acts as a bridge between the mother and the fetus. It provides the nutrients that the fetus needs to survive in the uterus and allows a species to live inside their mother until they are ready to be born. This means that babies are protected from the outside world until they are fully developed.

Examples of placental mammals

Humans, like most mammals, have a placenta they use to develop their young people. Animals, including mice, dogs, cows, bats and orcas, all have placentas.

This is different from marsupial mammals, which include opossums, kangaroos, wombs and koalas. They are provided a safe place to develop in their mother’s cover after birth until they are fully developed.

Find out more: On the death of the dinos, mammals already adopted earthly lifestyles

When have placental mammals evolved for the first time?

It is difficult to know the first placental mammal because the placentas are soft tissues and do not fossilize. The bones, which preserve, do not tell us if an animal held its young people inside the body.

“Placentas are difficult characteristics to know in the fossil file,” explains the mammals paleontologist Ornella C. Bertrand.

To discern if a mammal had a placenta, a pocket or something else, the researchers must look at other placental mammals and compare the characteristics which fossilize, for example, the teeth or the body of the body. This can also help scientists decide which mammals were somewhere between the two.

The first group of evolutionary placental mammals was a STEM group in the middle of the evolution of what was going to become a placental mammal. Eomia was the first in this group, and according to a study published in NatureThe Eutherian specimen had characteristics of the limbs and feet which would be useful for climbing and living in the trees, unlike the racing characteristics of the anterior non -placal Cretaceous eutheria.

Another early candidate, Juramaia, lived at the start of the Jurassic in China. He had a dental morphology similar to Eomia, However, the real age of the specimen was questioned in research.

When larger brains have developed

Although we did not know the first placental mammal certainly because of their low preservation potential, we know that around 55 million years ago, 10 million years after the extinction of dinosaurs, the placental mammals exploded in number while the marsupials decreased.

Carnivores, rodents and herbivores, all with placentas, have become the most important forms of mammals. Most initial groups have disappeared, with the exception of primates, whales and rodents.

After the explosion of their number, they grew up and finally, their brain also developed. Bertrand wrote in 2022 Science Study that their body size came before brain size around the eocene era.

It was not until later, “probably pulled by a need for greater cognition in increasingly complex environments,” explains Bertrand, that these creatures needed larger brains to control their body.

Why placental mammals have an evolutionary advantage

The benefit of a placenta is demonstrated by the fact that today there is around 5,000 placental mammals Against 334 marsupiaux.

“There must have been an advantage to have a placenta,” says Bertrand.

It could also be why some placental mammals have such complex brains. They have more time for gestation and form the large brains necessary to make their larger and more complex bodies work.

We do not know with certainty, but it may be that placental mammals had more chances of combat because they did not have to compete with so many species of dinosaurs. However, it should be noted that the marsupial mammals were doing well before the asteroid blow and not so well after.

It could also be that after the devastation that followed the success of the asteroid 66 million years ago, the placental mammals were not only tiny and potentially better capable of digging underground, they also had months to form the next generation inside the uterus, rather than treating the nuclear winter which occurred at their door.

Learn more:: The first mammal to live on earth Morganucodon or Brasilodon? Experts are still debating

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Sara Novak is a scientific journalist based in South Carolina. In addition to writing to discover, his work appears in Scientific American, Popular Science, New Scientist, Sierra Magazine, Astronomy Magazine and many others. She obtained a Baccalaureate in journalism from the Grady School of Journalism from the University of Georgia. She is also a candidate for a master’s degree in scientific writing from Johns Hopkins University.