One of the most significant events in the history of life was when fish evolved into tetrapods, crawling out of the water and eventually conquering land. The term tetrapod refers to four-limbed vertebrates, including humans.
To complete this transition, several anatomical changes were necessary. One of the most important was the evolution of hands and feet.
Working with researchers from the University of Quebec, in 2010 we discovered the first complete specimen of Elpistostege watsoni. This tetrapod-like fish lived more than 380-million-years ago, and belonged to a group called elpistostegalians.
Our research based on this specimen, published today in Nature, suggests human hands likely evolved from the fins of this fish, which we’ll refer to by its genus name, Elpistostege.
Elpistostegalians are an extinct group that displayed features of both lobe-finned fish and early tetrapods. They were likely involved in bridging the gap between prehistoric fish and animals capable of living on land.
Thus, our latest finding offers valuable insight into the evolution of the vertebrate hand.
Elpistostege, from the Late Devonian period of Canada, is now considered the closest fish to tetrapods (four-limbed land animals), which includes humans. Brian Choo
The best specimen we’ve ever found
To understand how fish fins became limbs (arms and legs with digits) through evolution, we studied the fossils of extinct lobe-finned fishes and early tetrapods.
Lobe-fins include bony fishes (Osteichthyes) with robust fins, such as lungfishes and coelacanths.
Elpistostegalians lived between 393–359 million years ago, during the Middle and Upper Devonian times. Our finding of a complete 1.57m Elpistostege – uncovered from Miguasha National Park in Quebec, Canada – is the first instance of a complete skeleton of any elpistostegalian fish fossil.
[embedded content]This animation shows what Elpistostege might have looked like when alive, and highlights the close similarities in its pectoral fin skeleton to the bones of our human arm and hand.
Prior to this, the most complete elpistostegalian specimen was a Tiktaalik roseae skeleton found in the Canadian Arctic in 2004, but it was missing the extreme-end part of its fin.
When fins became limbs
The origin of digits in land vertebrates is hotly debated.
The tiny bones in the tip of the pectoral fins of fishes such as Elpistostege are called “radial” bones. When radials form a series of rows, like digits, they are essentially the same as fingers in tetrapods.
The only difference is that, in these advanced fishes, the digits are still locked within the fin, and not yet free moving like human fingers.
Our recently uncovered Elpistostege specimen reveals the presence of a humerus (arm), radius and ulna (forearm), rows of carpal bones (wrist) and smaller bones organised in discrete rows.
We believe this is the first evidence of digit bones found in a fish fin with fin-rays (the bony rays that support the fin). This suggests the fingers of vertebrates, including of human hands, first evolved as rows of digit bones in the fins of Elpistostegalian fishes.
The pectoral fin of Elpistostege shows the short rows of aligned digits in the fin – an intermediate stage between fishes and land animals such as the early tetrapod Tulerpeton. Author provided
What’s the evolutionary advantage?
From an evolutionary perspective, rows of digit bones in prehistoric fish fins would have provided flexibility for the fin to more effectively bear weight.
This could have been useful when Elpistostege was either plodding along in the shallows, or trying to move out of water onto land. Eventually, the increased use of such fins would have lead to the loss of fin-rays and the emergence of digits in rows, forming a larger surface area for the limb to grip the land surface.
Our specimen shows many features not known before, and will form the basis of a series of future papers describing in detail its skull, and other aspects of its body skeleton.
Elpistostege blurs the line between fish and vertebrates capable of living on land. It’s not necessarily our ancestor, but it’s now the closest example we have of a “transitional fossil”, closing the gap between fish and tetrapods.
Our new specimen of Elpistostege watsoni measures 1.57 metres long from its snout to the tip of its tail. Richard Cloutier, UQAR
The full picture
The first Elpistostege fossil, a skull fragment, was found in the late 1930s. It was thought to belong to an early amphibian. In the mid 1980s the front half of the skull was found, and was confirmed to be an advanced lobe-finned fish.
The original finds of the Elpistostege skull roof (left) and front half of the skull. The new specimen confirms these all belong to the one species. Richard Cloutier/UQAR
Our new, complete specimen was discovered in the fossil-rich cliffs of the Miguasha National Park, a UNESCO World Heritage site in Eastern Canada. Miguasha is considered one of the best sites to study fish fossils from the Devonian period (known as the “Age of Fish”), as it contains a very large number of lobe-finned fish fossils, in an exceptional state of preservation.
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.
