Posted on 15 February, 2008 by Ed Yong
Their heads and bodies of bats have amassed an extraordinary array of adaptations that have make them lords of the night sky. Today, the thousand-plus types of bats make up a fifth of living mammal species. Richard Dawkins once described the evolution of bats as “one of the most enthralling stories in all natural history” and as of this week, the story has a clearer beginning.
The success of bats hinges on two key abilities: their mastery of flight, a feat matched only by birds and insects; and echolocation, the ability to navigate their way through pitch-blackness by timing the reflections of high-pitched squeaks. For evolutionary scientists, the big question has always been: which came first?
The ‘clawed bat’
Until now, fossil bats haven’t provided any clues for all of them show signs of both echolocation and flight. But a stunning new fossil, discovered by Nancy Simmons from the American Museum of Natural History is an exception and it provides a categorical answer to the long-running debate – the earliest bats could fly but could not echolocate.
The new creature hails from the Green River in Wyoming and is known as Onychonycteris, meaning “clawed bat”. Its fossils date back to about 52.5 million years ago and by comparing it to other prehistoric bats, Simmons found that it is the most ancient member of this lineage so far discovered. It acts as a ‘missing link’ in bat evolution, much like the famous Archaeopteryx hinted that birds may have evolved from dinosaurs.
Filed under: Animal behaviour, Animal evolution, Animal kingdom, Bats, Evolution, Mammals, Palaeontology | Tagged: bat evolution, Bats, echolocation, flight, fossils, nature, Onychonycteris, science | 2 Comments »
Posted on 14 January, 2008 by Ed Yong
For some dinosaurs, the best strategy was to grow fast and breed early. New fossil evidence suggests that at least three species, including celebrities like Tyrannosaurus and Allosaurus, were having sex in their teens. In this way, their pace of growth and maturity was closer to that of modern birds and mammals than it would be to a reptile scaled-up to the same size.
They also started to breed well before they had finished growing, which suggests that they lived relatively short and brutal lives and needed as much time as possible to reproduce before they met an untimely demise. Modern back-boned animals with high adult death rates use a similar strategy.
Filed under: Animal kingdom, Dinosaurs, Palaeontology | Tagged: Allosaurus, dinosaur growth, Dinosaurs, fossils, life history, medullary bone, reproductive strategy, science, T.rex, Tenontosaurus, Tyrannosaurus | 2 Comments »
Posted on 15 December, 2007 by Ed Yong
Cowboys have been lassoing cattle for several centuries, but it turns out that fungi developed the same trick 100 million years ago when dinosaurs still walked the Earth.
Alexander Schmidt and colleagues from the Humboldt University of Berlin found evidence of this ancient Wild West scene in a beautiful chunk of French amber.
The amber piece lacked the transparent clear beauty of a jeweller’s piece and the debris and dirt inside it suggests that it came from tree sap that had fossilised after it had fallen to the ground. There, it perfectly preserved the species living in the leaf litter, including a species of predatory fungi and the small worms – nematodes – that Schmidt thinks it hunted.
The fungus’s weapons were single cells coiled into rings just 10 micrometres in diameter. A thousand of these tiny loops could fit in a centimetre, but they were more than large enough to accommodate a blundering nematode. Once a worm swam through, the fungi constricted its snare, trapping the animal.
Filed under: Fungi, Palaeontology | Tagged: amber, carnivorous fungi, fossils, nematode, predatory fungi, science | 7 Comments »
Posted on 30 November, 2007 by Ed Yong
One of our extinct evolutionary cousins, Paranthropus robustus, may have walked like a man but it socialised like a gorilla. Using only fossils, UCL scientists have found that P.robustus males were much larger than females, competed fiercely for mates and led risky lives under heavy threat from predators.
I wrote an article about the cool new finding for Nature Network. Here’s the opening and you can read the full article here.
A single fossil can tell you about the shape, diet and movements of an extinct animal but with enough specimens, you can reconstruct their social lives too.
Charles Lockwood of University College London used an unusually large collection of fossils to peer back in time at the social structures of one of our closest extinct relatives, Paranthropus robustus, which inhabited southern Africa between 1.2 million and 2 million years ago.
Filed under: Animal behaviour, Animal kingdom, Evolution, Human evolution, Mammals, Palaeontology, Primates, Sex | Tagged: dimorphism, fossils, gorillas, Paranthropus robustus | Comments Off
Posted on 1 October, 2007 by Ed Yong
The sabre-toothed cat is one of the most famous prehistoric animals and there is no question that it was a formidable predator, capable of bringing down large prey like giant bison, horses, and possibly even mammoths. The two massive canines – the largest teeth of any mammal – are a powerful visual. But while they were clearly powerful weapons, scientists have debated their use for over 150 years.
Now, a new study shows that Smilodon, the most iconic of the sabre-tooths, had a surprisingly weak bite. They were a precision weapon that were used to deliver a single, final wound to an already subdued victim – the equivalent of an assasin’s stiletto rather than a swordsman’s blade.
Earlier suggestions pictured Smilodon using its teeth to hang onto the back of large prey, to slash their abdomens open, or to impale them at the end of a flying pouce. One of the most popular theories said that the cat would have used its teeth to sever arteries and airways with a decisive bite to the throat – a quicker technique than the suffocating neck bites used by modern lions.
Working out how strongly Smilodon could bite would go a long way towards deciding on one of these theories and to do that, palaeontologists have studied the animal’s fossilised skull. Even then, opinions have gone either way depending on which bit of the skull they looked at. The muscle attachment points suggest it has small jaw muscles, but the bite could have been powered from the neck. The lower jaw is smaller, but strongly built, lending weight to the idea of a powerful bite.
To get some clearer answes, Colin McHenry and colleagues from the University of Newcastle, Australia decided to put Smilodon‘s skull through a digital crash-test. They used a technique called ‘finite element analysis‘ or FEA, which is typically used in mechanical engineering and crash-testing for cars.
Filed under: Animal behaviour, Animal kingdom, Carnivores, Mammals, Palaeontology, Predators and prey | 3 Comments »
Posted on 20 September, 2007 by Ed Yong
In Jurassic Park, the role of Velociraptor was played by computer-generated reptilian actors, that bore little resemblance to the real deal. The actual dinosaur was smaller, slower and used its infamous claw to stab rather than disembowel. And now, scientists have found conclusive proof that it was covered in feathers.
Since Jurassic Park aired, dinosaurs like Velociraptor have received something of a makeover. It began in the late 1990s when Chinese palaeontologists found a stunning series of dinosaur fossils with distinct traces of feathers around their bodies. Some were just covered in a downy fluff, while others like Microraptor had fully-formed wings and were probably capable of true flight.
These species were primitive members of the dromaeosaurids, a group of small, agile predators that Velociraptor also belongs to. With feathered ancestors and evolutionary cousins, it was always extremely likely that Velociraptor also had a feathered coat but until now, that was always an educated guess.
The breakthrough came from Alan Turner and Mark Norell from the American Museum of Natural History and Peter Makovicky of the Field Museum of Chicago. They were studying the forearm of a Velociraptor unearthed in 1998, when they noticed six evenly spaced knobs of bone on the back edge.
The team recognised these as quill knobs, small lumps of bone that act as attachment points for feathers. These knobs are direct evidence that Velociraptor carried a row of feathers on its forearm, probably about 14 by Turner’s count. You can see them in the top two images above. The bottom two show the equivalent structures in a modern vulture, and how feathers are attached to them.
Filed under: Animal kingdom, Birds, Dinosaurs, Palaeontology | 6 Comments »
Posted on 12 September, 2007 by Ed Yong
The reasons why the Neanderthals died off remain a mystery. One of the major theories says that they were the victims of major climate changes, but new evidence suggests that this is an unlikely scenario.
In an age where climate change driven by our own hand is poised to cause catastrophic changes to human life, it seems fitting to work out if shifting climates also doomed our evolutionary cousins, the Neanderthals.
The question of why the Neanderthals died out has been the source of fierce debate since the first bones were discovered in the early 19th century. Some scientists turned the finger of blame inwards, suggesting that early humans killed them off, either directly, through violence and the spread of new diseases, or indirectly by gradually out-competing them.
Others have accused changing climates. According to them, Neanderthals were adapted to cold environments and, being less flexible than humans, they were unable to cope with a warming post-Ice Age world.
Now, Chronis Tzedakis from the University of Leeds has found compelling evidence that the Neanderthals extinction was unlikely to have coincided with the extreme shifts in climate at the end of the last Ice Age.
While their findings don’t rule out the climate change model completely, they strongly suggest that it wasn’t a major factor in the Neanderthals’ downfall.
Filed under: Climate change, Geology, Palaeontology | 2 Comments »