The 15m-long megalodon died out about 3.6 million years ago, and a million years earlier than long thought, scientists say. Image / 123RF
The 15m-long megalodon died out about 3.6 million years ago, and a million years earlier than long thought, scientists say. Image / 123RF
The giant prehistoric predator that inspired Hollywood's latest piece of low-brow sharksploitation became extinct much earlier than first thought – and it was today's great whites that drove its demise.
The 15m-long Megalodon – meaning "big tooth" and brought to life in Jason Statham movie The Meg, which was incidentally filmed in West Auckland – died out about 3.6 million years ago, and a million years earlier than long thought.
A recent study attempted to link that long-assumed extinction date with a supernova thought to have occurred around that time.
But another team of US and UK scientists now conclude that the fossil record simply wasn't good enough to state that the beast roamed oceans beyond 3.6 million years ago.
"After making extensive adjustments to this worldwide sample and statistically re-analysing the data, we found that the extinction of O. megalodon must have happened at least one million years earlier than previously determined," said Robert Boessenecker, vertebrate palaeontologist at the College of Charleston.
The revised date meant the megalodon likely went extinct long before a suite of strange seals, walruses, sea cows, porpoises, dolphins and whales all disappeared sometime between one million and 2.5 million years ago.
Great white sharks first showed up with serrated teeth about six million years ago and only in the Pacific; by four million years ago, they were found around the world.
"We propose that this short overlap was sufficient time for great white sharks to spread worldwide and out-compete O. megalodon throughout its range, driving it to extinction-rather than radiation from outer space."
New Caledonian crows already have a reputation for being pretty clever. Photo / Supplied
New Caledonian crows have a reputation of being some of the smartest birds on the planet – not least for using tools to solve complex challenges devised by scientists.
Now researchers have found that these wily creatures can plan three steps ahead of achieving a goal, in a way that's similar to how we plan future moves in chess.
They set up problems to determine if the crows were solving the task on a moment-to-moment basis or were truly planning out a sequence of behaviours before they took on the task.
For example, in one problem crows had to use a short stick to push a stone from a tube, and then drop this stone on to a platform to release a piece of meat.
They had to do this while ignoring a long stick in a tube, as the long stick did not work in the platform.
To make the problem even harder, and ensure the crows were truly planning, only one stage of the problem could be viewed at a time.
This meant the crows had to remember where the stone, long stick and meat were and use this information to plan out the correct sequence for a solution.
"Because each part of the problem was out of sight of the others, our study clearly shows the birds were capable of preplanning," said Romana Gruber, a PhD student at the University of Auckland who worked alongside colleagues from the University of Cambridge and the Max Planck Institute for the Science of Human History.
"They were imagining the required steps in advance rather than simply acting on a moment-to-moment basis."
Dr Alex Taylor, also of the University of Auckland, said the study contributed significantly to our knowledge of how widespread planning with tools is across the animal kingdom.
"The ability of humans to plan ahead while using tools is a key reason why we currently have the civilisation we live in today," Taylor said.
"To see a bird species also possesses this combination of abilities is remarkable."
Hive minds
Bees can do basic maths, scientists say. Photo / File
In other clever creature news: researchers have revealed that bees can do basic mathematics, in a discovery that expands our understanding of the relationship between brain size and brain power.
Building on their finding that honeybees can understand the concept of zero, Australian and French researchers set out to test whether bees could perform arithmetic operations like addition and subtraction.
Solving maths problems requires a sophisticated level of cognition, involving the complex mental management of numbers, long-term rules and short term working memory.
The revelation that even the miniature brain of a honey bee can grasp basic mathematical operations has implications for the future development of Artificial Intelligence, particularly in improving rapid learning.
Led by researchers from Australia's RMIT University the new study showed bees can be taught to recognise colours as symbolic representations for addition and subtraction, and that they can use this information to solve arithmetic problems.
RMIT's Associate Professor Adrian Dyer said numerical operations like addition and subtraction are complex because they require two levels of processing.
"You need to be able to hold the rules around adding and subtracting in your long-term memory, while mentally manipulating a set of given numbers in your short-term memory," Dyer said.
"On top of this, our bees also used their short-term memories to solve arithmetic problems, as they learned to recognise plus or minus as abstract concepts rather than being given visual aids.
"Our findings suggest that advanced numerical cognition may be found much more widely in nature among non-human animals than previously suspected.
"If maths doesn't require a massive brain, there might also be new ways for us to incorporate interactions of both long-term rules and working memory into designs to improve rapid AI learning of new problems."
