Tag Archives: paleonthology

Artist impression of the newly discovered Ikrandraco avatar. Image: Scientific Reports

Ancient flying reptile was a cross between dragon and pelican

Artist impression of the newly discovered  Ikrandraco avatar. Image: Scientific Reports

Artist impression of the newly discovered Ikrandraco avatar. Image: Scientific Reports

Paleontologists have discovered a new pterosaur species in 120-million-year-old rocks at two sites in northeastern China.  The flying reptile was dubbed Ikrandraco avatar, where draco is Latin for “dragon,” and Ikran are the pterosaurlike flying beasts depicted in the 2009 blockbuster Avatar.

The ancient reptile was described in paper published in the journal Scientific Reports as having a deep lower jaw with a a thin, crescent-shaped keel.  At the end of this bony keel, the researchers note a peculiar hook-shaped projection – an unique feature never before seen in any other pterosaur or vertebrate for that matter – that might have served as an anchor for soft tissue. These suggest that the Ikrandraco may have sported a pelicanlike throat pouch which the flying reptile would have used to carry fish gleaned from lakes or other waters.

I’m note sure how much of the artist representation from above is speculative art or factual representation. If the latter’s the case, then damn this Ikrandraco was one interesting beast!

 

 

 

The 200-kilogram 'bear otter' is one of several large carnivores that became extinct around 2 million years ago. ILLUSTRATION BY VICTOR LESHYK

Early humans responsible for ancient carnivore wipe-out in Africa, not climate change

sabre_tooth_cat

Millions of years ago, the wild savannas of Africa were teeming with carnivore wildlife, much more diverse than what we see today: lions, hyenas and other large-bodied carnivores. Paleontologist Lars Werdelin at the Swedish Museum of Natural History in Stockholm suggests the carnivore species decimation that began roughly two million years ago can be attributed to the intervention of early human ancestors that began eating meat at the time, consuming both prey and predator.

Over the past few thousands of years human intervention has led to the extinction of a number of species,  ranging from moas—giant, flightless birds that lived in New Zealand—to most lemurs in Madagascar. Plants and water creatures weren’t spared either.Where and when humans or their ancestors began to make dramatic changes to the ecosystem is a matter of debate that has remained largely unresolved.

The 200-kilogram 'bear otter' is one of several large carnivores that became extinct around 2 million years ago. ILLUSTRATION BY VICTOR LESHYK

The 200-kilogram ‘bear otter’ is one of several large carnivores that became extinct around 2 million years ago. ILLUSTRATION BY VICTOR LESHYK

Fossil records collected  from eastern and southern Africa, like Lothagam on the western shore of Lake Turkana in northern Kenya , reveal that some seven million years ago the plains of Africa were dominated by varied group of carnivores: sabertooth cats, strange long-legged hyenas, giant bear dogs (members of an extinct family of carnivores called Amphicyonidae), a leopard-size member of the mustelid family to which badgers belong, as well as small  carnivores related to today’s civets and mongooses also prowled there. Four million years ago, other carnivores began to surface: hyena species ancestral to the brown hyena found in southern Africa today,  modern-looking big cats, early spotted hyenas, several dog species, giant otters that have no modern counterpart, a giant civet and a variety of smaller carnivores.

After peaking around 3.5 million years ago, the number of large carnivore species declined gradually over the next million and a half years or so, mostly because the rate at which new species originated slowed down while the extinction rate held steady. Still, carnivores reigned supreme, and our flimsy ancestors,   such as Australopithecus afarensis, whose brain and body were only a bit bigger than a chimp’s,  where really no match to the great families of ancient carnivores.

A hungry hominin

Illustration of Homo Erectus.

Illustration of Homo Erectus.

Starting with  Homo erectus, the first hominin that actually resembles modern humans, things began to change. Homo erectus ate meat, congregated with peers and used tools, like sharp stones. Oddly or not, some 1.5 million years ago, corresponding to the presence of Homo erectus, carnivore species began to massively die out. Some scientists believe climate change was responsible, others like Werdelin believe early humans had the biggest part to play in this massacre. There are however somethings that don’t add up, despite the timing.

” If competition with H. erectus was to blame, then the steep decline in eastern Africa’s large carnivore species should have started well before 1.5 million years ago becauseH. erectus had emerged by nearly 1.9 million years ago. Species numbers are a blunt instrument at best for tracking the progress of an entire order of mammals over time because a reduction in numbers of one of its group can be masked by an increase in another. If two sabertooth species go extinct but are replaced by lions and leopards, the numbers will remain the same, but the community will have undergone a major change because lions and leopards can take a broader range of prey than sabertooths could,” says Werdelin.

Werdelin reasoned that a better way to measure carnivore diversity is not just to look at the number of species, but on how diverse their roles in the ecosystem are as well. The cats, for example, are highly adapted to eating meat and thus qualify as hypercarnivores. But other carnivores are omnivorous—dogs, for example, will eat a wide variety of food in addition to meat. Still others, such as raccoons, are hypocarnivores, eating very little meat and subsisting mainly on fruits and vegetables.

Carnivore species in Africa today – a mere fraction compared to ancient times

To visualize the  diversity of form  Werdelin and colleagues performed  a statistical analysis, thereby creating a two-dimensional plot that  he calls the morphospace. This morphospace represents the diversity of form (and inferred function) that exists within a group of related organisms, in this case the carnivores that lived in Africa over the past 3.5 million years. Plotting separate morphospaces for carnivores from distinct time intervals and comparing them offers a sense of how carnivore anatomy and eating habits shifted over time.

As reported in a paper published in the journal PLOS ONE, it appears the large carnivore families that occupy eastern Africa today represent only a fraction of the morphospace of the carnivores in the 3.5-million- to three-million-year interval, when species diversity was at its highest. According to Werdelin, these carnivores  lost nearly 99 percent of its so-called functional richness, which is to say today’s carnivores fill far fewer kinds of ecological roles than their predecessors did.  This dramatic decrease began  in the interval between two million and 1.5 million years ago, which means that the process must have started before that time—bringing the onset of this major decline in line with the origin of H. erectus.

Some researchers contest this idea, however, reasoning that H. erectus was neither numerous enough to cause these changes, nor hungry enough for meat (controversial findings).

“Like any nascent hypothesis, this one comes with a series of problems that need resolution. The most significant of these issues concerns the timing of the events described here, both in terms of when the carnivores began going downhill and when humans started to pose a competitive threat to them. We need a clearer picture of what happened and when to draw firm conclusions about cause and effect. In addition, scientists do not know whether hominins were sufficiently numerous and competitive to cause such massive change to the carnivore community,” says Werdelin.

Werdelin believes collecting more fossils from the   2.5-million- to two-million-year time interval or more refined techniques for analyzing the fossils  already found today might help better pinpoint when carnivores started to decline in eastern Africa.

“I hope that researchers skeptical of my hypothesis will come up with some ingenious ways of testing it. To that end, another aspect of this idea bears mention. Attempts to explain ecosystem change typically provide a bottom-up perspective, looking at how climate factors affect plants and how changes in those organisms affect the rest of the food chain up to the top predators. My hypothesis about eastern Africa’s large carnivores provides a top-down view, considering how change in the top predators could affect the primary producers at the bottom of the food chain, such as grasses and trees,” Werdelin says.

Images of fossils belonging to the enantiornithine genus. Feathers on the primitive bird's hind legs provide evidence of an extra pair of wings. (c) Xiaoting Zheng et al/Science

Ancient bird species had four wings

Images of fossils belonging to the enantiornithine genus. Feathers on the primitive bird's hind legs provide evidence of an extra pair of wings. (c) Xiaoting Zheng et al/Science

Images of fossils belonging to the enantiornithine genus. Feathers on the primitive bird’s hind legs provide evidence of an extra pair of wings. (c) Xiaoting Zheng et al/Science

Though we’ve accomplish our knowledge a great deal in the past decades of bird evolution there are still many loose ends and debate is far from being settled. A general consensus among paleontologists is that birds today are actually a sort of modern dinosaurs, now recent fossils findings from China suggest early birds some 150 million years ago were four-winged creatures. It’s rather unclear at this point whether these newly confirmed species were precursors to modern birds or represent a distinct lineage that died out.

The 11 specimens discovered by researchers from the  Shandong Tianyu Museum of Natural History in China provide the first solid evidence that early birds also adopted a four winged structure before ditching the hind-limb feathers in favor of a presumably more efficient flight capability. The basal bird specimens, which included Sapeornis, Yanornis and Confuciusornis species, lived some 150 million years ago, and it was during this time that the researchers believe the animals were reading to use their hind limbs for terrestrial locomotion.

The conclusions come after  pennaceous feathers – a type of plumage that is  long, stiff and asymmetrically that is typically employed by modern birds today in their wings to aid flight – were sighted neatly preserved in the hind-legs of the fossils. This suggests that these basal birds used four wings to fly or glide, and overtime discarded one of their pair of wings. The findings seem consisting with other previous discoveries, like feathers found on the back and legs of a bird fossil from the Archaeopteryx genus in 2004, that suggest early birds may have first adapted four-winged flight.

The aerodynamics of these four-winged  fossils remain debatable, partly because of it’s highly difficult to interpret the specimens in two dimensions since the exact location and displacement of the basal birds’ feathers can’t be seen. The researchers believe nevertheless that “there is circumstantial data that might be useful in inferring the distribution and orientation of leg feathers.”

“If an animal has big feathers on its legs and feet, it’s definitely something that’s not good for fast running,” said Xing Xu from Linyi University in Shandong province.

Today birds still have feathers on their hind-legs, but these are far from being suite for flight, instead they serve to protect and insulate. Moreover the feathery, fluffy bits are very sparse as the rest of the leg is scaly.

The four-winged fossils were described in a paper published in the journal Science.

Triceratops horridus skeleton at the American Museum of Natural History in New York City

Youngest dinosaur found adds weight to asteroid extinction theory

Paleontologists have unearthed in Montana the fossilized bone of a the last known dinosaur  so far, dating back from 65.5 million years ago. The finding carries a big weight in supporting the currently leading asteroid impact dinosaur extinction theory.

Triceratops horridus skeleton at the American Museum of Natural History in New York City

Triceratops horridus skeleton at the American Museum of Natural History in New York City

What paleontologists found was actually the horn of a thought to be triceratops in a sediment bank while hunting for fossils the Hell Creek Formation, a 100m-thick slab of mudstone in south eastern Montana. The region is famous for fossil findings which range from both before and after the extinction period. Other dinosaur fossils found up to now were either much older, or were unearthed after being washed from their original graves into much younger sediments, long after they died.

Although the theory of an asteroid hitting the Yucatan peninsula around 65 million years ago has been so far regarded as the most plausible one by the scientific community, little evidence has been found up until now, apart from the giant crater itself whose date perfectly corresponds with the dinosaur extinction period. The 18-inch-long horn, however, was found and dated 5 inches below the K-T boundary, the geological line in sedimentary rock that signifies the impact of the asteroid. The latest fossil was discovered a mere 13cm below that line.

This suggests that the dinosaur—and, likely, other dinosaurs—may have been alive shortly before the asteroid hit. Other finds from recent years uncovered fossils and even T. rex footprints in the timeline extinction gap, some less than a foot below the K-T boundary, but none have narrowed the gap as much as this discovery has.

“This demonstrates that dinosaurs did not go extinct prior to the impact and that at least some dinosaurs were doing very well right up until we had the impact,” paleontology grad student Tyler Lyson, the study’s lead author, told the Guardian.

Scientists warn however that this leading has come from only one bone and further research and uncovering must be made before a sturdy conclusion can be formulated. Some researchers suspect more such fossils are waiting to be found.