Shortly after the transition from sea to land, our ancestors who lay eggs must have started raising their young.
The first fossil was so surprising that Brian Hebert almost missed the second. Tucked into the trunk of a 300 million-year-old tree was an orderly line of vertebrae, which encompassed a series of delicate and sensitive ribs.
A piece of abdominal scales covered the space below, paving the way for a pelvis and a pair of beautiful thigh bones. These were the first known remains of Dendromaya unmikinesis, a vertebrate that inhabited the Earth and probably resembled a long-standing monitor lizard.
“I can close my eyes and remember it as if it were yesterday,” says Hasbert, who happened in a tree in Cape Breton, Nova Scotia in 2017, “It was three-dimensional just in front of my face.” “
Then, Hebert noticed another set of bones, which left him dead: a small skull an inch long, which was nested in a place where a left femur joined with a pubic bone. This skull, Hebert felt, belonged to a teenager who was probably against his mother.
Dendromaya anamkensis fossil recovered from the trunk of a tree in 2017. The juvenile skull can be seen in panel B, just below the left femur, near the right corner. (Madin et al., Nature Ecology and Development, 2020)
Hebert did not know at that time, but what he found would soon become the Prime test in an article published today in the journal Nature Ecology and Evolution that states that parental care: investing in offspring after birth Resources – At least 306 million years.
Rich in today’s amniotes, groups that include mammals, birds and reptiles infest their young. While the evolutionary strategy is expensive, it increases the chance that an animal’s progeny will succeed, and researchers believe that breeding is characteristic of modern animals.
But this ancient fossil couple, dating back to the pre-dinosaur era, when our ancestors who laid eggs first dragged the ashes, suggests that this nutritional behavior originated much more deeply in this branch of the tree of life. Is implicit
“We tend to think of animals [in this part of the past as ‘primitive’ or ‘simple’,” says Jackie Lungmus, a vertebrate paleontologist at the University of Chicago, who was not involved in the study. “But they deserve more credit. Still these animals were probably doing a lot of the work that animals still do today.”
Before leaving Stump, Hebert, who had been looking for fossils in the landscape of Nova Scotia since his childhood, knew that he had discovered something big.
To confirm this finding, paleontologists Hilary Madin and Arjan Mann were recruited, who carefully transferred the bones to their laboratory at Carleton University, Ottawa, for a more detailed analysis.
Under the microscope, the fossils were infallible in nature, says Mann. They belonged to two individuals of the same species, one fully developed and the other young, and had the distinctive feature of the extinct family of the pre-mammal ancestor.
The varanópidos, with reptile features that lived about 300 million years ago. But adults looked different enough from their relatives to earn their own gender name: Dendromaya, or “mother in the tree.”
The exaggeration of the fossils indicated that the couple had died suddenly, perhaps during a storm that flooded their strong base, preserving their last moments in the frozen frame. Leaning between the tail and the hind leg of the adult, the small specimen appeared as if it were protecting it from damage.
“It looks a lot like denying the behavior,” says Maddin, who found it difficult not to think of a protective mother who is raising her son.
A representation of the fossil of Dendromaya anammakensis, labeled in several parts of the anatomy. The juvenile specimen is marked, the position near the adult’s thigh bone (Fe) and the pelvis (Pu). (Madin et al. Nature Ecology and Evolution, 2019).
Mann, his graduate student, joked casually that he found “early evidence of parental care.” He joked, but his words reminded Madine of a similar fossil in South Africa a decade ago: the Hellesorus specimen that was surrounded by four tails during the Permian 260 million years ago, died with a tail.
Although separated by some 45 million years, both fossils were varrenopid, and both, apparently, died while harboring smaller versions of themselves.
The researchers who documented the Heliosorus had pointed out the remains to Mann and Madine as a possible family group, making them more reliable and older. Mann had attacked not a key phrase, but a viable hypothesis: from its earliest days, Warnopids would have preferred child rearing.
Some researchers have also previously presented older evidence of parental care in invertebrates, but dendromaya may represent the first known example of a young father who is a living child.
Without the time machine, researchers could not know what these animals were doing at the time of their death. After all, the behavioral evidence cut in the study “is not something that is preserved in the rocks,” says Stephanie Drumheller-Horton, a vertebrate zoologist at the University of Tennessee, Knoxville, who is not participating in the study.
For example, it is possible that two Dendromaya are not a family unit, but two unskilled refugees seeking a safe harbor against a storm. Vertebrate paleontologist Eva Hoffman of the American Museum of Natural History, which was not included in the study, points out that similar powers have been seen previously among unrelated adults and adolescents in the fossil record.
Even the wrapping tail guarantees nothing: perhaps both had little space. Until more examples of possible associations of parents and children arise, says Hoffman, caution can be exercised.
But Drumheller-Horton believes that a mother who cuddles with her child remains the most likely explanation. Fossil placement was also unlikely to be a coincidence. Bones are not introduced in such intimate settings.
And if both Dendromaya and Heliosaurus were guardians, “that tells us that this behavior could have existed in a common ancestor of this group,” says Madin. Perhaps paleontologists have yet to discover the most affectionate mothers and fathers.
Whatever was clearly trapped around its origins, education and its advantages. In many ways, this is a sensible strategy, says Mann. By transporting their children at an early age, ancient animals helped ensure their survival and the continued persistence of generations to come.
“Parental care is a strategy with a long seniority,” he says. “Clearly, it has worked many times in evolutionary history. And we should appreciate it. A Carboniferous-period fossil found in Nova Scotia, Canada, shows an ancient creature called the varnopid synopsid (family Varnopidae) caring for its young.
“Parental care is a behavioral strategy where parents make an investment or divert resources by themselves to increase their chances of health and survival for their offspring,” said paleontologist Professor Hilary Madin and her colleagues at Carlton University And told Funkar Treasures.
“While there are a variety of parental care strategies, long-term postnatal care is the most expensive for a parent.” “This form of parental care is particularly common in mammals, as all mammalian offspring demand nutrition from their mothers.”
“However, there is still little understanding of the evolutionary history of this behavior.” 305 million year old specimen of Dendromaya unmykinesis. Image credit: Madin et al, doi: 10.1038 / s41559-019-1030-z
Professor Madin’s team found the remains of an adult creature and an allied juvenile within the stump of a tree tree on Cape Breton Island, Nova Scotia.
The specimen not only represents a new species, but also belongs to an entirely new genus Vernopid synapsid. The researchers named the ancient animal Dendromaya namakimenesis. “This is the earliest evidence of long-term postnatal care in a vertex,” Professor Madin said.
“The adult animal appears to hide and protect the juvenile in a den. Today this behavior is very common in mammals. “
“It is interesting to see this animal, leading to mammals on the evolutionary line, displaying this behavior so quickly.”
This discovery is reported in a paper in the journal Nature Ecology and Evolution.