Ancient mammals had mostly dark brown coats during the dinosaur era, new study reveals

Inayat Singh · CBC News

· Posted: Mar 16, 2025 4:00 AM EDT | Last Updated: 10 minutes ago

Ancient mammals that lived successful the clip of dinosaurs were mostly the aforesaid dark-brown colour, according to a caller survey providing clues astir however those mammals evolved arsenic they faced elephantine predators.

The study, published successful the diary Science, utilized technological techniques that person likewise shown the colouring of assorted dinosaurs and past birds from their fossils. Advances successful dinosaur cognition person trickled into museums and fashionable depictions of the animals implicit the past years, thing the caller study's authors anticipation tin present hap for past mammals.

"Just the mode the archetypal colour representation successful an extinct dinosaur opened the doorway to a full caller country of inquiry, this insubstantial besides does that. And that's beauteous exciting," said co-author Julia Clarke, a vertebrate paleontologist astatine the University of Texas astatine Austin.

Using six well-preserved fossil specimens and almighty microscopy, the researchers were capable to observe the signifier of pigment-producing parts of cells known as melanosomes. Previous enactment has shown that signifier corresponds to the colour of the animal's fur. 

Apart from gathering a clearer representation of those aboriginal mammals, knowing the colour is besides a immense breakthrough, according to Clarke, for knowing different aspects of the animals' lives and however they evolved implicit the millennia. Present-day mammals, portion not arsenic colourful arsenic birds, bash person much assortment than those aboriginal mammals.

"We cognize however important colours are for animals," said co-author Lilian D'Alba, an evolutionary biologist astatine the Naturalis Biodiversity Center successful Leiden, Netherlands. 

"It's a mode for animals to interact with their environment. Colours tin besides archer america overmuch astir however these organisms interact with temperature, humidity, with different organisms. And truthful we we tin get a batch of accusation from looking astatine colours."

Why colour matters

Coat colours successful mammals are important for galore things, according to D'Alba, similar controlling their assemblage temperature, hiding from predators utilizing camouflage, and being a marker of aggressiveness oregon spot to different animals. 

D'Alba said that aboriginal probe could look astatine however mammals got much colourful coats — aft a large extinction event, about 66 cardinal years ago, killed disconnected dinosaurs, their large predators.

"The mammals that survived abruptly recovered themselves successful a spot wherever determination was plentifulness of space. They had caller places to colonize," she said. This was successful opposition to the lives of mammals during the clip of dinosaurs, erstwhile they are believed to person been progressive mostly astatine night, successful the darkness, and relied much heavy connected senses of odor and interaction alternatively than vision.

"So a batch of caller antithetic types of lifestyles evolved. And with these lifestyles, caller environments, you spot … an detonation of caller taxon successful mammals."

The insubstantial suggests that these caller taxon came with caller colours, for each the expanded activities these caller mammals could present do.

"It's agelong been the presumption that Mesozoic mammaliaforms were nocturnal, hiding successful the acheronian to debar being devoured by the galore predatory dinosaurs and different animals would person snacked connected these small animals. But, this fur colouration survey is the archetypal to find wide enactment for this crossed each the fossils sampled," said Hans Larsson, subordinate prof and curator of vertebrate palaeontology astatine McGill University, who was not progressive with the study.

Mesozoic mammaliaforms are aboriginal mammals that lived during the clip of the dinosaurs.

He said the findings are absorbing successful knowing however being nocturnal whitethorn person led to the aboriginal improvement of galore different things mammals have, including our ample brains, eyesight, hearing, reproductive biology and parental care.

"Ecologically, it's absorbing due to the fact that it suggests mammaliaforms were capable to instrumentality vantage of a nocturnal manner for millions of years and cleanable it to the constituent that mammals are the ascendant nocturnal predators of galore of today's ecosystems," Larsson said.

Fossils recovered successful China

Doing probe connected the colours of past animals tin beryllium a crippled of waiting and luck, according to D'Alba. The insubstantial relied connected six fossil specimens recovered successful China, which has a fewer areas of the cleanable geology to find these kinds of fossils. 

That's capable to gully an inference for astir mammals during that era, according to Caleb Brown, curator of dinosaur systematics and improvement astatine the Royal Tyrrel Museum successful Drumheller, Alta.

"Most dinosaurs are known from little than 1 skeleton, but yet we we marque inferences astir their taxonomy," helium said.

"We person to unrecorded with that, but we besides person to support moving connected collecting much fossils due to the fact that arsenic you get much and much fossils, your statistical powerfulness increases."

At the moment, China is wherever these fossils, with preserved tegument oregon hairsbreadth oregon feathers are being found, according to D'Alba and Brown. A batch of it depends connected luck.

"There's a suite of deposits successful China that sphere fundamentally water deposits oregon volcanic ash deposits, and these are precise good grained sediments and precise accelerated burial," Brown said. 

"And successful those cases it's rather communal to find dinosaurs with feathers, but besides mammals with with hair."

D'Alba hopes probe volition proceed connected the mammals to larn much astir those colours … and spot that ending up depicted successful fashionable culture.

"The past [Jurassic Park movie] was really rather breathtaking for maine due to the fact that they showed feather, feathered dinosaurs, and immoderate of them had the patterns that we predicted," D'Alba said. 

"It's ever bully to spot that immoderate of the accuracy of our studies is is reaching the public."