Tag Archives: vertebrate

Ancient Vertebrate Ancestors: The Surprising Discovery of Four Eyes

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Illustration of Haikouichthys, a Cambrian fish

Illustration of Haikouichthys, a notable Cambrian fish with fossilized evidence of a second pair of eyes

Xiangtong Lei, Sihang Zhang

Over 500 million years ago, the earliest known vertebrates exhibited an intriguing feature: an extra eye. Interestingly, humans may retain traces of this ancient evolutionary trait.

Significant fossils from two species of jawless fish, known as myllokunmingids, were discovered by Kong Peiyun. From 2019 to 2024, Kong worked alongside colleagues at Yunnan University in China, specifically around Dianchi Lake.

The fossils unearthed in the Chengjiang biota area, renowned for its exquisite preservation, date back to approximately 518 million years ago—a timeframe marked by a dramatic increase in life’s diversity during the Cambrian period.

Remarkably, the vertebrate fossils discovered by Kong’s team included well-preserved soft tissue and vital eye structures.

Complex eye structures evolved independently in various animal groups. Many invertebrates, like insects, possess compound eyes, which consist of numerous individual units, each with its own lens, enabling a mosaic vision.

Meanwhile, vertebrates such as humans and reptiles possess what scientists label as “camera eyes.” These comprise a spherical lens, retina, iris, and muscles that regulate eye movement. Additionally, they contain pigment structures called melanosomes that influence eye color.

Light focuses on the retina, generating a signal relayed to the brain via the optic nerve.

Under electron microscopy scrutiny, Kong and his team identified two eyes situated on the sides of the head, with melanin-rich melanosomes preserved, alongside two smaller enigmatic black marks between them.

Employing a lens impression to analyze the fossils, team members led by Jacob Vinther from the University of Bristol suggested that these ancient creatures possessed two pairs of camera-like eyes, allowing them to visualize their environment much like modern vertebrates. The decisive difference? They utilized four eyes instead of two.

Fossil of Haikouichthys displaying conserved melanosomes

Xiangtong Lei, Sihang Zhang

The research team posits that this ancient additional eye has evolved into various organs known as the pineal complex. Some vertebrates, such as reptiles, possess a light-sensitive organ called the parietal eye atop their heads, while all mammals retain a reduced version that is the pineal gland, a key player in regulating sleep cycles through melatonin secretion.

“Early vertebrates likely used the pineal organs as functional eyes, enabling them to perceive their surroundings before evolving into sleep-regulating organs,” states Vinther.

These large eyes may have been optimized for high-resolution vision, complemented by smaller eyes that enabled detection of nearby threats—critical for survival in the predator-rich Cambrian seas.

According to Vinther, these creatures could likely discern objects with detail, estimating their shape and gain a degree of depth perception—all thanks to their remarkable four-eyed adaptation.

Tetsuto Miyashita, from the Canadian Museum of Nature in Ottawa, finds the interpretation of these fossils both “half-believable and half-doubtful.”

The structure located between the two eyes had previously perplexed researchers, but realizing it may indicate another camera eye was considered a “lightbulb” moment, he explains.

If indeed this is the case, it raises the question: where is the animal’s nose? “Most early fish evolution centered around nose development, suggesting that it would be unusual for the nose to not be preserved,” he notes.

Miyashita anticipates significant discussions will persist until experts can engage in a thorough debate regarding this exciting finding. “What function do so many prominent eyes actually serve?” he questions.

John Patterson, a researcher from the University of New England in Armidale, Australia, asserts that it is logical for prey species to have developed such visual capabilities to escape formidable predators.

The Cambrian era was evolutionary peculiar, showcasing animals displaying unusual behavior and not strictly developing pairs of eyes on their heads, but placing eyes in other regions as well.

Karma Nangle, a professor at the University of California, Riverside, aims to create a comprehensive map of the entire fossil body to investigate the potential existence of similar traces. Such findings could demonstrate that the second set of eyes may simply be a result of chemical processes during fossilization.

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Source: www.newscientist.com

Paleontologists Uncover Earliest Evidence of Ancient Honey Bees Nesting in Vertebrate Fossil

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Bees exhibit an extraordinary range of species and behavior, from solitary types that nest in burrows to social variants that construct intricate nests. This nesting diversity is partially captured in the fossil record, with trace fossils dating from the Cretaceous to the Holocene. In a recent study, Field Museum paleontologist Lázaro Vignola López and his colleagues unveil novel nesting behaviors based on trace fossils unearthed from Late Quaternary cave deposits on the Caribbean island of Hispaniola. Osnidam Almontei was discovered within the cavity of a vertebrate corpse.

A reenactment of the life of bees with evidence of them building their nests in caves and using the bone cavities as housing chambers for several egg-laying cells. Image credit: Jorge Mario Macho.

“The initial descent into the cave isn’t very deep. You secure a rope to the side and rappel down,” Dr. Vignola López explained.

“Entering at night, you can spot the eyes of tarantulas residing there. As you navigate through the 10-meter-long underground tunnel, fossils start to emerge.”

Fossil layers were separated by carbonate deposits formed during rainy periods in antiquity.

Although rodents made up most of the fossils, remains of sloths, birds, and reptiles—over 50 species in total—were also found. Together, these fossils narrate a compelling story.

“We hypothesize this cave served as a home for owls over generations, potentially for hundreds or even thousands of years,” Dr. Vignola López remarked.

“The owl would venture out to hunt and return to the cave to regurgitate pellets.”

“We’ve collected fossils of the prey the owl consumed, its own remains, and even bones of turtles and crocodiles that may have inadvertently fallen into the cave.”

Dr. Vignola López and his colleagues observed that the sediments in empty tooth sockets of mammalian jaws didn’t accumulate randomly.

“The surface was notably smooth and slightly concave, which is unusual for sediment burial. I noticed this pattern across multiple specimens and thought to myself, ‘There’s something peculiar here.’ It reminded me of a hornet’s nest,” he noted.

Many well-known nests constructed by bees and wasps belong to social species that coexist in large colonies, raising their young together—like the bees in honeycombs or paper wasp nests.

“However, the majority of bee species are solitary. They deposit eggs in small cavities and leave pollen for their larvae’s nourishment,” Dr. Vignola López continued.

“Some bee species create nests in tree hollows, in the ground, or utilize vacant spaces. Certain species in Europe and Africa even nest within discarded snail shells.”

To investigate the possible insect nests within the cave fossils, the researchers conducted CT scans and X-rays of the bones, capturing 3D images of the compacted soil in the tooth sockets without damaging the fossils.

The shape and composition of the deposits bore similarities to mud nests created by some contemporary bee species. Some of these nests contained ancient pollen grains that mother bees had sealed for their larvae.

The researchers propose that bees combined saliva and soil to construct small nests for their eggs, smaller than the eraser on a pencil.

Nesting within larger animal bones provided protection for bee eggs from potential predators such as wasps.

While the bees themselves were not preserved, the unique characteristics of the nests allowed for a taxonomic classification.

They named the nests Osnidam Almontei, in honor of the scientist Juan Almonte Milan, who first discovered this cave.

“Since no bee remains were found, they may have belonged to a currently existing species. Our knowledge on the ecology of various bee species in these islands is limited,” Dr. Vignola López stated.

Scientists speculate that this behavior arises from a combination of factors. With little soil covering the limestone terrain in this region, bees may have opted for caves as their nesting sites, rather than digging into the ground like many other species.

Additionally, this cave had been home to generations of owls, with numerous owl pellets accumulating over the years, providing the bees with ample use of the bones the owls left behind.

“This finding illustrates the peculiarities of bees. They can be surprising, and it emphasizes the importance of meticulous examination when studying fossils,” Dr. Vignola López remarked.

of paper published today in Proceedings of the Royal Society B Biological Sciences.

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Lazaro W. Vignola-Lopez and others. 2025. Fossil traces in mammal remains reveal a new nesting behavior for bees. R Soc Open Science 12(12):251748; doi: 10.1098/rsos.251748

Source: www.sci.news

Jawed vertebrate fossils dating back 400 million years discovered in Australia bring mystery to light

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Palaeospondylus ganniwas a small, eel-like creature that lived during the mid-Devonian period, about 390 million years ago, and is among thousands of similarly preserved fossils from the Achanaras Quarry in Caithness, Scotland. is represented by. Radically different interpretations of its structure had assigned this species to almost all major jawless and jawed vertebrate groups. Paleontologists are currently identifying new and old species. spondylosis From the early Devonian period of Australia.

Palaeospondylus australisbrain cases and histological sections. Image credit: Barrow others., doi: 10.1093/nsr/nwae444.

First described in 1890, spondylosis It is a mysterious fish-like animal with a series of strange morphological features in the fossil record, including a lack of teeth and osteodermal bones.

Until now it was only known as Palaeospondylus ganni From the Middle Devonian Orcadian Basin in Scotland.

Initially interpreted as jawless vertebrates, they were soon classified into their own order and family.

Whereas the Scottish specimen was extremely compressed with all skeletal elements welded together, the new discovery spondylosisis located in a 400-million-year-old limestone in the Georgina Basin of western Queensland, central Australia, and is in a very different state of preservation as a 3D unfractured element.

“This is an amazing addition to Queensland's fossil record and is at the other end of the size scale of prehistoric giants like dinosaurs.” loetosaurus and Australotitan couperensis'' said Carol Barrow, a paleontologist at the Queensland Museum.

“What? Palaeospondylus australis Even more interesting is its relationship with similar species in northern Scotland. Palaeospondylus ganni”

The new fossil's honeycomb-like structure and complex internal features suggest the fish's early evolutionary importance.

The exact relationship is Palaeospondylus australis Although much remains unclear, as its features indicate that it retains many larval features, it is likely to be a distant relative of sharks.

This groundbreaking discovery not only enriches our understanding of ancient Australian ecosystems, but also highlights the global connectivity of early vertebrates across continents.

research Palaeospondylus australis It promises to uncover more mysteries about the evolution of jawed vertebrates.

“Discovery of a mysterious animal” spondylosis The early Devonian discovery in Australia indicates that this form is likely to have been distributed globally, given that Scotland and eastern Australia were then and now on opposite sides of the globe. “, the paleontologists said.

“New evidence regarding neurocranial features… spondylosis Adds important but contradictory information about that affinity. ”

“Until new and better evidence becomes available, spondylosis It is considered a pedunculate gnathostome, possibly a sister group to the cartilaginous fishes, and shows a mosaic of characters exhibited by both the osteoostia and some placoderms, as well as by the cartilaginous and teleost fishes. ”

of result appear in the diary National Science Review.

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Carol J. Barrow others. 3D brain box of early jawed vertebrates spondylosis From Australia. National Science Reviewpublished online on December 3, 2024. Doi: 10.1093/nsr/nwae444

Source: www.sci.news

Research: Vertebrate Brain Resembles an Ancient Retrovirus

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Biologists from the Altos Institute, Cambridge Institute of Science, and the University of Cambridge have discovered that genetic elements derived from retroviruses (retrotransposons) are essential for the production of myelin (the insulating sheath that surrounds nerve axons) in mammals, amphibians, and animals. I discovered that fish. This gene sequence, called retromyelin, is likely the result of an ancient retroviral infection, and comparisons of retromyelin in mammals, amphibians, and fish indicate that retroviral infection and genome invasion events occurred separately in each of these groups. suggests that it has occurred.

gauche other. suggest that retrovirus internalization played an important role in the emergence of vertebrate myelin. Image credit: Ghosh other., doi: 10.1016/j.cell.2024.01.011.

Myelin, the complex fatty tissue that lines vertebrate nerve axons, allows rapid impulse conduction without the need to increase axon diameter. This means that the nerves can be packed more closely together.

It also provides metabolic support for the nerves, allowing them to lengthen.

Myelin first appeared on the tree of life around the same time as the jaw, and its importance in vertebrate evolution has been recognized for a long time, but until now it is unclear what molecular mechanism caused its appearance. was.

Tanay Ghosh and colleagues at Altos Labs-Cambridge Institute of Science noticed the role of retromyelin in myelin production while studying the gene networks used by oligodendrocytes, the cells that produce myelin in the central nervous system. .

Specifically, they were studying the role of non-coding regions, including retrotransposons, in these gene networks. This has not been previously studied in the context of myelin biology.

“Retrotransposons make up about 40% of our genome, but we know nothing about how they helped animals acquire specific traits during evolution.” said Dr. Ghosh.

“Our motivation was to learn how these molecules serve evolutionary processes, especially in the context of myelination.”

Researchers discovered that in rodents, retromyelin RNA transcripts regulate the expression of myelin basic protein, one of the key components of myelin.

When we experimentally inhibited retromyelin in oligodendrocytes and oligodendrocyte progenitor cells (the stem cells from which oligodendrocytes are derived), the cells were no longer able to produce myelin basic protein.

To find out whether retromyelin is present in other vertebrate species, scientists looked for similar sequences within the genomes of jawed vertebrates, jawless vertebrates, and some invertebrate species. Searched for.

They identified similar sequences in all other classes of jawed vertebrates (birds, fish, reptiles, amphibians) but found no similar sequences in jawless vertebrates or invertebrates. did not.

Robin Franklin, a neuroscientist at the Altos Institute at the Cambridge Institute of Science, said: “There was an evolutionary drive to speed up the conduction of impulses in axons, because the faster the impulse conduction, the faster we can grab objects and move away from them.'' Because they can run away.”

Next, the authors wanted to know whether retromyelin was integrated once in the ancestor of all jawed vertebrates, or whether there were separate retroviral invasions in different branches.

To answer these questions, they constructed a phylogenetic tree from 22 jawed vertebrate species and compared their retromyelin sequences.

This analysis revealed that retromyelin sequences are more similar within species than between species, suggesting that retromyelin has been acquired multiple times through a process of convergent evolution.

The researchers also showed that retromyelin plays a functional role in myelination in fish and amphibians.

When they experimentally disrupted the retromyelin gene sequence in fertilized zebrafish and frog eggs, they found that the developing fish and tadpoles produced significantly less myelin than normal.

“Our findings open new avenues of research exploring how retroviruses are involved in directing evolution more generally,” said Dr. Ghosh.

of study It was published in the magazine cell.

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Tanai Ghosh other. 2024. Retroviral involvement in vertebrate myelination through retrotransposon RNA-mediated control of myelin gene expression. cell 187 (4): 814-830; doi: 10.1016/j.cell.2024.01.011

Source: www.sci.news

Is the Brazilian flea toad the world’s smallest vertebrate?

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Flea frog perching on 1 Brazilian Real (coin diameter is 27 mm)

Renato Gaiga

The tiny Brazilian frog, about the size of a pea, could threaten the current record holder for the world's smallest vertebrate.

flea toad Brachycephalus purex (actually a species of frog) was first described by scientists in 2011. Immediately after that, Mirko Sole Researchers at Brazil's Santa Cruz State University thought this species might be the smallest amphibian ever discovered. But only a few specimens have been collected from the frog's only known habitat, a forested hilltop in southern Bahia, Brazil. Also, the necessary gonad tests to determine whether they were adults were not performed.

Solé and his colleagues measured the lengths of 46 flea toads, examined their gonads, and checked for the presence of throat clefts, which only males have, to determine the frogs' maturity and gender.

adult B. Purex Males have an average body length of over 7 millimeters and are slightly smaller than females. Therefore, they are smaller than males. Phaedophryn amauensisa frog from Papua New Guinea that was previously considered both the smallest amphibian and the smallest vertebrate.

Say “It's perfectly clear.” mark schartz At the Danish Natural History Museum in Copenhagen. “These may actually be the world's smallest living frogs, which is amazing.”

It's not just the average size that's shocking, the smallest specimens in the study show just how small these flea frogs are compared to other minifrogs. “It's 6.45 mm.” [long]That's 30 percent smaller than any adult male frog I've ever seen,” Schertz said. “It's almost a millimeter smaller than the next smallest frog.”

At such small scales, frogs develop strange anatomical peculiarities, such as missing toes and underdeveloped ears. they cannot hear their suitor's song. Some species have very weak balance organs and are barely able to jump.

But Solé says there may also be smaller vertebrates that have yet to be discovered. Perhaps the next record holder could be another small frog or a parasitic male deep-sea anglerfish.

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Source: www.newscientist.com