Lampreys are boneless, blood-sucking snake-like fish considered to be “living fossils” that have barely changed since they first arose during the Paleozoic era, more than 100 million years before the first dinosaurs.
Interestingly, since the 1800s, scientists have thought that the earliest ancestors of all vertebrates, including ourselves, resembled lampreys’ worm-like babies.
Now, recently discovered baby lamprey fossils have overturned that popular evolutionary theory, which some scientists were already starting to question, reports a Canadian-led study published in the latest issue of the journal Nature.
It turns out that baby lampreys from the Paleozoic era, which had been “missing” from the fossil record until now, don’t look the way scientists had previously hypothesized — raising new questions about what our ancestors were really like.
Why scientists thought our ancestors were like baby lampreys
To be sure, adult lampreys seem like an unlikely candidate for what the progenitor of vertebrates might have looked like.
They’re alien-looking predators with a sucker-like mouth ringed with multiple rows of sharp teeth that they use to pierce the skin of their prey — usually other fish — and suck out their blood. One species, the sea lamprey, has devastated fisheries in the Great Lakes since invading them in the early 1900s via shipping canals.
This is an adult sea lamprey, a species that has invaded the Great Lakes and devastated fisheries there by sucking the blood of other fish, often killing them in the process. Lampreys have no bones, only cartilage, so they didn’t fossilize well. (photo credit: T. Lawrence GLFC)
But lampreys aren’t born monsters. Their babies or larvae are tiny, blind, worm-like creatures called ammocoetes that burrow in the mud and slurp algae and rotting organic matter floating by.
They also have an uncanny resemblance to worm-like animals called lancelets that don’t have a backbone, but do have many other characteristics of vertebrates, the group that includes fish, amphibians, reptiles, birds and mammals. That puts lancelets just on the other side of the border between vertebrates and invertebrates like worms, snails and insects.
This is the ammocoete or larva of a modern Pacific lamprey. It is a tiny, blind, filter-feeding worm-like animal that lacks the large eyes, sucker mouth and teeth of the adult. (Gregory Kovalchuk)
The lancelet Amphioxides is seen under the microscope. Lancelets are worm-like animals that don’t have a backbone, but share many other characteristics with vertebrates. Ammocoetes have a physical resemblance to lancelets. (D. Kucharski K. Kucharska/Shutterstock)
Biologists also believed that the larval or embryonic development of some animals was, in some ways, a look back through time at their evolution. For example, human embryos have a tail and gill-like structures around their necks.
All that led scientists to theorize about what the ancestor of all vertebrates — from fish to fowl to humans — might have looked like.
Tetsuto Miyashita, a research scientist at the Canadian Museum of Nature in Ottawa who led the new study, says that since the 19th century, when people looked at ammocoetes, “the common wisdom was that we were looking at… our distant ancestors in the face.”
Gap in the fossil record
It’s not a flattering thought, but it was a popular one up until several years ago..
That’s when researchers such as Margaret Docker, a professor in the department of biological sciences at the University of Manitoba, began to question the evidence.
For one thing, scientists hadn’t found ammocoete fossils dating back earlier than 125 million years ago, even though the earliest lamprey fossils known are 360 million years old.
So, did early lampreys even have an ammocoete stage?
“There were just none of the earlier stages apparent,” said Docker, who wasn’t involved in the new study. She published a paper with two other scientists in 2018 suggesting that early lampreys either didn’t have a larval stage or only had a very short one, but noted they weren’t the first to be thinking of that.
“For the longest time, I sort of just came to the conclusion that we would never really know for sure.”
Tetsuto Miyashita (right) stands with researcher Rob Gess in 2016 atop the shale deposit in Makhanda, South Africa that has yielded fossils of the 360 million-year-old Priscomyzon lamprey. Many other invertebrate and plant fossils have been found at this site. (Tetsuto Miyashita)
That’s because lampreys don’t fossilize well, as they have no bones, only cartilage. They only form compressed fossils under very specific conditions, similar to those that preserved soft-bodied ancient creatures in Canada’s Burgess Shale, said Philippe Janvier, emeritus director of research at the French Centre National de la Recherche Scientific (CNRS) in an email.
“Such fossils have long been regarded as barely more informative than a squashed slug on a highway,” said Janvier, who co-authored the 2018 paper with Docker. It was hard to tell whether any of them were ammocoetes or juveniles in the middle of metamorphosing into adults.
How the gap was filled
Still, Miyashita was determined to have a closer look at that fossil evidence to see if the theory about ancient ammocoetes was true, so he went looking where the oldest known lamprey fossil had been found: a site in South Africa called Waterloo Farm.
Back in the Paleozoic, South Africa was located at the South Pole, but it was much warmer and wasn’t always iced over. At that time, Waterloo Farm was a coastal lagoon teeming with fish and invertebrates, which made up most of the animals on Earth at that time, when the ancestors of modern amphibians were just starting to take their first steps out of the water and onto land.
Miyashita got in touch with the local expert there, Robert Gess, a paleontologist and research associate at the Albany Museum and Rhodes University in Makhanda, South Africa. Gess had rescued 100 tonnes of shale that contained thousands of fossil specimens at Waterloo Farm before the construction of a local road.
Fossil of the hatchling of Priscomyzon, from the Paleozoic era around 360 million years ago. The hatchling is already equipped with large eyes and toothed sucker, which in modern lampreys only develop in adults. (The Canadian 25-cent coin offers a size comparison for the tiny fossil). (Tetsuto Miyashita/Canadian Museum of Nature)
Miyashita wanted to see if there were very small lampreys or ammocoetes in the rocks.
Gess managed to spot seven, all smaller than the smallest ones he had previously found, Miyashita recalled — the tiniest of them “the size of your little fingernail.”
Despite that, the researchers could see that it was clearly a lamprey, with huge eyes for spotting prey and a sucker mouth with sharp teeth like adult lampreys today.
But it wasn’t an adult. Upon closer inspection, that fossil had a little bulge on its belly.
With excitement, the researchers realized that it was a yolk, which many fish carry with them to feed them when they first hatch, Miyashita said: “This baby fossil lamprey just hatched out of the egg.”
An artist’s reconstruction shows the life stages of the fossil lamprey Priscomyzon riniensis. It lived around 360 million years ago in a coastal lagoon in what is now South Africa. Clockwise from right: A tiny, yolk-sac carrying hatchling with its large eyes; a juvenile; and an adult showing its toothed sucker. (Kristen Tietjen)
Janvier, who wasn’t involved in the study, agreed that the bulge was clearly a yolk sac, similar to those found in many fossil hatchlings of other fish.
When Miyashita went through museum collections of other ancient lamprey fossils, he found hatchlings of other species that also looked like mini-adults.
It was clear evidence that ancient lampreys didn’t have a worm-like larval stage. While the adults might be “living fossils,” the ammocoetes evolved later.
Docker estimates it happened around 300 million years ago, since modern lamprey species all have an ammocoete stage, suggesting their common ancestor from that time already had the trait. That period was when many insects and amphibians also developed very different juvenile and adult stages in different environments, such as water and land, with a metamorphosis in between.
At that time, plants had colonized the land, creating and stabilizing soils with their roots, making freshwater environments less prone to wild fluctuations and raging floods, and therefore more habitable.
But it was still an environment with few predators — one where tiny baby animals could safely grow.
Miyashita searched the collections of other museums and found other ancient lamprey hatchlings with similar features. This is a Pipiscius zangerli hatchling that lived 309 million years ago, from the Mazon Creek fossil beds in Illinois, U.S.A. It also had large eyes, a toothed sucker, and a yolk sac showing it had just hatched. (Tetsuto Miyashita)
Miyashita said developing a larval stage capable of colonizing those safe freshwater environments probably “was the key for the survival of modern lamprey lineages.”
What it means for the story of our evolution
Miyashita said the fossil discovery has big implications for theories about the evolution of vertebrates. Clearly, ammocoetes don’t look the way they do because of a resemblance to the ancestor of all vertebrates, as previously thought.
“It’s not exactly often that just a single set of tiny fossils can just completely overturn that accepted scenario of vertebrate evolution,” he said. “I think this is one important step toward figuring out what our distant ancestors actually looked like 500 million years ago.”
Both Janvier and Docker agree that the discovery is important, even if some scientists had already suspected it before. Docker called it “quite exciting.”
“There’s a big difference between thinking it and having the clear evidence,” she said. “So it’s certainly a big deal.”
NAIROBI, Kenya (AP) — The body of Ugandan Olympic athlete Rebecca Cheptegei — who died after being set on fire by her partner in Kenya — was received Friday by family and anti-femicide crusaders, ahead of her burial a day later.
Cheptegei’s family met with dozens of activists Friday who had marched to the Moi Teaching and Referral Hospital’s morgue in the western city of Eldoret while chanting anti-femicide slogans.
She is the fourth female athlete to have been killed by her partner in Kenya in yet another case of gender-based violence in recent years.
Viola Cheptoo, the founder of Tirop Angels – an organization that was formed in honor of athlete Agnes Tirop, who was stabbed to death in 2021, said stakeholders need to ensure this is the last death of an athlete due to gender-based violence.
“We are here to say that enough is enough, we are tired of burying our sisters due to GBV,” she said.
It was a somber mood at the morgue as athletes and family members viewed Cheptegei’s body which sustained 80% of burns after she was doused with gasoline by her partner Dickson Ndiema. Ndiema sustained 30% burns on his body and later succumbed.
Ndiema and Cheptegei were said to have quarreled over a piece of land that the athlete bought in Kenya, according to a report filed by the local chief.
Cheptegei competed in the women’s marathon at the Paris Olympics less than a month before the attack. She finished in 44th place.
Cheptegei’s father, Joseph, said that the body will make a brief stop at their home in the Endebess area before proceeding to Bukwo in eastern Uganda for a night vigil and burial on Saturday.
“We are in the final part of giving my daughter the last respect,” a visibly distraught Joseph said.
He told reporters last week that Ndiema was stalking and threatening Cheptegei and the family had informed police.
Four in 10 women or an estimated 41% of dating or married Kenyan women have experienced physical or sexual violence perpetrated by their current or most recent partner, according to the Kenya Demographic and Health Survey 2022.
TEL AVIV, Israel (AP) — A rare Bronze-Era jar accidentally smashed by a 4-year-old visiting a museum was back on display Wednesday after restoration experts were able to carefully piece the artifact back together.
Last month, a family from northern Israel was visiting the museum when their youngest son tipped over the jar, which smashed into pieces.
Alex Geller, the boy’s father, said his son — the youngest of three — is exceptionally curious, and that the moment he heard the crash, “please let that not be my child” was the first thought that raced through his head.
The jar has been on display at the Hecht Museum in Haifa for 35 years. It was one of the only containers of its size and from that period still complete when it was discovered.
The Bronze Age jar is one of many artifacts exhibited out in the open, part of the Hecht Museum’s vision of letting visitors explore history without glass barriers, said Inbal Rivlin, the director of the museum, which is associated with Haifa University in northern Israel.
It was likely used to hold wine or oil, and dates back to between 2200 and 1500 B.C.
Rivlin and the museum decided to turn the moment, which captured international attention, into a teaching moment, inviting the Geller family back for a special visit and hands-on activity to illustrate the restoration process.
Rivlin added that the incident provided a welcome distraction from the ongoing war in Gaza. “Well, he’s just a kid. So I think that somehow it touches the heart of the people in Israel and around the world,“ said Rivlin.
Roee Shafir, a restoration expert at the museum, said the repairs would be fairly simple, as the pieces were from a single, complete jar. Archaeologists often face the more daunting task of sifting through piles of shards from multiple objects and trying to piece them together.
Experts used 3D technology, hi-resolution videos, and special glue to painstakingly reconstruct the large jar.
Less than two weeks after it broke, the jar went back on display at the museum. The gluing process left small hairline cracks, and a few pieces are missing, but the jar’s impressive size remains.
The only noticeable difference in the exhibit was a new sign reading “please don’t touch.”
VICTORIA – The British Columbia government is partnering with a bear welfare group to reduce the number of bears being euthanized in the province.
Nicholas Scapillati, executive director of Grizzly Bear Foundation, said Monday that it comes after months-long discussions with the province on how to protect bears, with the goal to give the animals a “better and second chance at life in the wild.”
Scapillati said what’s exciting about the project is that the government is open to working with outside experts and the public.
“So, they’ll be working through Indigenous knowledge and scientific understanding, bringing in the latest techniques and training expertise from leading experts,” he said in an interview.
B.C. government data show conservation officers destroyed 603 black bears and 23 grizzly bears in 2023, while 154 black bears were killed by officers in the first six months of this year.
Scapillati said the group will publish a report with recommendations by next spring, while an independent oversight committee will be set up to review all bear encounters with conservation officers to provide advice to the government.
Environment Minister George Heyman said in a statement that they are looking for new ways to ensure conservation officers “have the trust of the communities they serve,” and the panel will make recommendations to enhance officer training and improve policies.
Lesley Fox, with the wildlife protection group The Fur-Bearers, said they’ve been calling for such a committee for decades.
“This move demonstrates the government is listening,” said Fox. “I suspect, because of the impending election, their listening skills are potentially a little sharper than they normally are.”
Fox said the partnership came from “a place of long frustration” as provincial conservation officers kill more than 500 black bears every year on average, and the public is “no longer tolerating this kind of approach.”
“I think that the conservation officer service and the B.C. government are aware they need to change, and certainly the public has been asking for it,” said Fox.
Fox said there’s a lot of optimism about the new partnership, but, as with any government, there will likely be a lot of red tape to get through.
“I think speed is going to be important, whether or not the committee has the ability to make change and make change relatively quickly without having to study an issue to death, ” said Fox.
This report by The Canadian Press was first published Sept. 9, 2024.
