BREAKING Pearson gold heist suspect arrested after flying into Toronto from India
Another suspect is in custody in connection with the gold heist at Toronto Pearson International Airport last year, police say.
Tusks are a striking feature of many animals -- elephants, hippos, warthogs, walruses -- and are often sought-after by humans.
But no birds, fish or reptiles today sport this extreme and ever-growing bit of anatomy. Only mammals do, even though they weren't the first tusked creatures. It is an ancient trait that predates dinosaurs, a new study has found.
"We were able to show that the first tusks belonged to animals that came before modern mammals, called dicynodonts," said Ken Angielczyk, a curator at Chicago's Field Museum and an author of the new study, in a news release. "They're very weird animals."
Ranging from the size of a rat to elephantine, the dicynodonts lived from about 270 million to 201 million years ago. While their closest living relatives are mammals, they looked more reptilian, with turtle-shaped heads.
Dicynodonts were the most abundant and diverse vertebrates before the rise of the dinosaurs, and they all had a pair of tusks protruding from their upper jaws.
Before digging into how exactly tusks evolved, the researchers had to define exactly what a tusk is and how it differs from a tooth -- something that had been ambiguous.
They determined that a tusk must extend from the mouth, consist solely of a substance called dentine and continue to grow throughout an animal's life -- even if it gets damaged. Teeth are also made from dentine. However, they are coated in enamel. This, along with their shape, makes them durable, but once adult teeth grow in, there's not much that can be done if they do break. They don't regrow.
"Enamel-coated teeth are a different evolutionary strategy than dentine-coated tusks -- it's a trade-off," said Megan Whitney, postdoctoral fellow at Harvard University's department of organismic and evolutionary biology. She was the lead author of the study.
The researchers then analyzed thin sections of 19 fossilized tusks of dicynodonts, representing 10 different species found in South Africa, Antarctica, Zambia and Tanzania. They also used micro-computerized tomography scans to examine how the fossils were attached to the skull, and whether their roots showed evidence of continuous growth. They found that while a few of the dicynodonts studied had true tusks, with no enamel, the rest had big teeth.
The scientists also found there wasn't a strict progression from non-tusks to tusks. Different members of the dicynodont family evolved tusks independently at different times, and some never evolved true tusks.
"I fully expected there to be a single moment in dicynodont evolutionary history where tusks evolved because that's the simplest explanation. However, we found convergent evolution of tusks later in dicynodont evolution," Whitney said. Convergent evolution is when similar features evolve independently in different species or different periods in time.
For tusks to evolve, they found that a flexible ligament attaching the tooth to the jaw was needed, as well as reduced rates of teeth replacement -- a combination of features that today is uniquely found in modern mammals.
"It all ladders up to giving us a better understanding of the tusks we see in mammals today," said Angielczyk, speaking of the research, which published in the journal Proceedings of the Royal Society B Biological Sciences.
Another suspect is in custody in connection with the gold heist at Toronto Pearson International Airport last year, police say.
Hailey and Justin Bieber are going to be parents. The couple announced the news on Thursday on Instagram, both sharing a video that showcases Hailey Bieber's growing belly.
A family of fifth generation farmers from Ituna, Sask. are trying to find answers after discovering several strange objects lying on their land.
A Conservative government led by Pierre Poilievre would not legislate on, nor use the notwithstanding clause, on abortion, his office says, as anti-abortion protesters gather on Parliament Hill.
A southwestern Ontario woman has received an $8,400 bill from a hospital in Windsor, Ont., after she refused to put her mother in a nursing home she hated -- and she says she has no intention of paying it.
Studies have shown that ultraprocessed foods can have a detrimental impact on health. But 30 years of research show they don’t all have the same impact.
Miss Teen USA resigned Wednesday, sending further shock waves through the pageant community just days after Miss USA said she would relinquish her crown.
Ontario Provincial Police confirm one person has died after a single-vehicle rollover crash in Sharbot Lake, Ont. that seriously injured five others.
A grieving mother is speaking out after her 36-year-old son was shot and killed in North Preston, N.S., Wednesday night.
A Listowel, Ont. man, drafted by the Hamilton Tigercats last week, is also getting looks from the NFL, despite only playing 27 games of football in his life.
A small Ajax dessert shop that recently received a glowing review from celebrity food critic Keith Lee is being forced to move after a zoning complaint was made following the social media influencer’s visit last month.
The Canada Science and Technology Museum is inviting visitors to explore their poop. A new exhibition opens at the Ottawa museum on Friday called, 'Oh Crap! Rethinking human waste.'
The Regina Police Service says it is the first in Saskatchewan and possibly Canada to implement new technology in its detention facility that will offer real-time monitoring of detainees’ vital health metrics.
The stakes have been set for a bet between Vancouver and Edmonton's mayors on who will win Round 2 of the Stanley Cup playoffs.
A grieving mother is hosting a helmet drive in the hopes of protecting children on Manitoba First Nations from a similar tragedy that killed her daughter.
A chicken farmer near Mattawa made an 'eggstraordinary' find Friday morning when she discovered one of her hens laid an egg close to three times the size of an average large chicken egg.
A P.E.I. lighthouse and a New Brunswick river are being honoured in a Canada Post series.
An Ontario man says he paid more than $7,700 for a luxury villa he found on a popular travel website -- but the listing was fake.