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Jaekelopterus rhenaniae
#1
Temnospondyl Wrote:Jaekelopterus rhenaniae

[Image: seascorpion_closeup.jpg]

Temporal range: 390 Ma Middle Devonian

Scientific classification 
Kingdom: Animalia
Phylum: Arthropoda
Class: Merostomata
Order: †Eurypterida
Family: †Pterygotidae
Genus: †Jaekelopterus
Species: Jaekelopterus rhenaniae

Jaekelopterus rhenaniae ("Otto Jaekel's wing from the Rhineland") is an extinct species of the Eurypterida (sea scorpions). At an estimated length of 2.5 meters (8.2 feet), it is one of the two largest arthropods ever discovered (the other is a giant millipede-like animal, Arthropleura, although which animal was larger is unclear)

[Image: original.png]

The second largest eurypterid known is Pterygotus. Jaekelopterus lived approximately 390 million years ago. Although called a "sea scorpion", it is speculated to have lived in fresh water rivers and lakes, rather than in saltwater seas. The animal was described by Simon Braddy and Markus Poschmann of the University of Bristol in the journal Biology Letters (November 2007); they found a 46 cm chelicera (claw-like mouth part), and estimated the total size of the animal based on the proportions of this claw. When extended, the chelicerae would have added another meter to its length.
The animal's fossilized remains were discovered in the Early Devonian (Emsian) Klerf Formation Lagerstätte of Willwerath near Prüm, Germany.



my clay Jaekelopterus 
[Image: original.jpg]

Temnospondyl Wrote:Jaekelopterus rhenaniae measured some 8.2 feet (2.5 meters) long, scientists estimate, based on the length of its 18-inch (46-centimeter), spiked claw.

The find shows that arthropods—animals such as insects, spiders, and crabs, which have hard external skeletons, jointed limbs, and segmented bodies—once grew much larger than previously thought, said paleobiologist Simon Braddy of the University of Bristol in the United Kingdom.

"This is an amazing discovery," Braddy said.

"We have known for some time that the fossil record yields monster millipedes, supersized scorpions, colossal cockroaches, and jumbo dragonflies," he added. "But we never realized, until now, just how big some of these ancient creepy-crawlies were."
The newfound fossil creature is estimated to be at least one and a half feet (46 centimeters) longer than any previously known prehistoric sea scorpion, a group called eurypterids.
Braddy and co-author Markus Poschmann of the Mainz Museum in Germany report the find in the latest issue of the journal Biology Letters.
Poschmann uncovered the fossilized claw in a quarry near Prüm in Germany.
Rock layers encasing it suggest the creature lived in a brackish coastal swamp or river delta, the researchers said.

Temnospondyl Wrote:http://www.prehistoric-wildlife.com
Name: Jaekelopterus ‭(‬Jeakel's wing‭).
Phonetic: Jee-kel-op-teh-rus.
Classification: Arthropoda,‭ ‬Merostomata,‭ ‬Eurypterida,‭ ‬Pterygotidae.
Species: J.‭ ‬rhenaniae‭ (‬type‭)‬.
Diet: Carnivore.
Size: Estimated‭ ‬2.5‭ ‬meters long.
Known locations: Germany‭ ‬-‭ ‬Klerf Formation.
Time period: Emsian of the Devonian.
Fossil representation: Single chelicerae.

       Named after Otto Jeakel,‭ ‬Jaekelopterus is currently the largest known sea scorpion,‭ ‬even bigger than the more famous Pterygotus.‭ ‬Again this demonstrates how the arthropods grew to giant proportions which continue to remain unknown in today‭’‬s living arthropods.‭ ‬Jaekelopterus itself it thought to have been a freshwater species that possibly hunted other arthropods and possibly fish.
       The upper size estimate of Jaekelopterus was extrapolated by comparing the size of the chelicerae to other more complete specimens and then scaling up the size of the compared specimens to reveal the size.‭ ‬The problem with this method is that it is only as reliable as the similarity between the compared specimens,‭ ‬and caution needs to be exercised when using it.‭ ‬This caution was also reflected by the authors of the discovery,‭ ‬Simon Braddy and Markus Poschmann,‭ ‬who estimated the length of Jaekelopterus at‭ ‬2.5‭ ‬meters,‭ ‬even though comparison scaled it closer to‭ ‬2.6‭ ‬meters in length.

Temnospondyl Wrote:http://scienceblogs.com
The fossil record has yielded various gigantic arthropods, in contrast to their diminutive proportions today. The recent discovery of a 46cm long claw (chelicera) of the pterygotid eurypterid ('sea scorpion') Jaekelopterus rhenaniae, from the Early Devonian Willwerath Lagerstätte of Germany, reveals that this form attained a body length of approximately 2.5m--almost half a metre longer than previous estimates of the group, and the largest arthropod ever to have evolved. Gigantism in Late Palaeozoic arthropods is generally attributed to elevated atmospheric oxygen levels, but while this may be applicable to Carboniferous terrestrial taxa, gigantism among aquatic taxa is much more widespread and may be attributed to other extrinsic factors, including environmental resources, predation and competition. A phylogenetic analysis of the pterygotid clade reveals that Jaekelopterus is sister-taxon to the genus Acutiramus, and is among the most derived members of the pterygotids, in contrast to earlier suggestions.[Image: scorpion_claw.jpg]
This isn't some casual graspy sort of claw, either—it's a great spiky wicked looking claw, with pointy daggery bits sticking out that make it look like some medieval weapon of terror.
This is a much more Lio-like creature than the dainty little bug in the cartoon. I wouldn't mind having one of these for a pet myself! It's too bad they've all been dead for 390 million years.

Temnospondyl Wrote:Science Daily
[big]The discovery of a giant fossilised claw from an ancient sea scorpion indicates that when alive it would have been about two and a half meters long, much taller than the average man. [/big]
This find, from rocks 390 million years old, suggests that spiders, insects, crabs and similar creatures were much larger in the past than previously thought.

Dr Simon Braddy from the Department of Earth Sciences at the University of Bristol, co-author of an article about the find, said, 'This is an amazing discovery. We have known for some time that the fossil record yields monster millipedes, super-sized scorpions, colossal cockroaches, and jumbo dragonflies, but we never realised, until now, just how big some of these ancient creepy-crawlies were.'

The claw was discovered by one of Dr Braddy's co-authors*, Markus Poschmann, in a quarry near Prüm in Germany.

Poschmann described finding the fossil: "I was loosening pieces of rock with a hammer and chisel when I suddenly realised there was a dark patch of organic matter on a freshly removed slab. After some cleaning I could identify this as a small part of a large claw. Although I did not know if it was more complete or not, I decided to try and get it out. The pieces had to be cleaned separately, dried, and then glued back together. It was then put into a white plaster jacket to stabilise it."

The claw is from a sea scorpion (eurypterid) Jaekelopterus rhenaniae that lived between 460 and 255 million years ago. It is 46 centimetres long, indicating that the sea scorpion to which it belonged was around 2.5 metres (8 feet) long -- almost half a metre longer than previous estimates for these arthropods and the largest one ever to have evolved.

Eurypterids are believed to be the extinct aquatic ancestors of scorpions and possibly all arachnids.

Some geologists believe that giant arthropods evolved due to higher levels of oxygen in the atmosphere in the past. Others, that they evolved in an 'arms race' alongside their likely prey, the early armoured fish.

'There is no simple single explanation', explains Braddy. 'It is more likely that some ancient arthropods were big because there was little competition from the vertebrates, as we see today. If the amount of oxygen in the atmosphere suddenly increased, it doesn't mean all the bugs would get bigger.'

*The research is published online in the Royal Society's journal Biology Letters. 

[Image: 071120195710.jpg]
[small]Mock up of fossil sea scorpion, compared to man. (Credit: Simon Powell)[/small]

Taipan Wrote:Giant Ancient Sea Scorpions Had Bad Eyesight

By Tanya Lewis, Staff Writer   |   July 08, 2014 07:01pm ET

Gigantic sea scorpions that lurked in the ocean more than 400 million years ago weren't as scary as they sound, a new study suggests.

The massive creatures, known as pterygotids, were the largest arthropods that ever lived, growing to be up to 6.5 feet (2 meters) long, with claws measuring up to about 2 feet (0.6 m). But contrary to what scientists thought, these animals may not have been true top predators.

"These things were almost certainly still predators of some kind, but the imagined notion that they were swimming around terrorizing anything that looked edible is probably an exaggeration," said Derek Briggs, a paleontologist at Yale University in New Haven, Connecticut, and co-author of the new study, published today (July 8) in the journal Biology Letters. 

Pterygotids were a type of eurypterid, an extinct type of sea scorpion related to arachnids. These ocean-dwelling creatures lived between about 436 million to 402 million years ago, in the Silurian and Devonian periods, Briggs said. Their closest living relatives are horseshoe crabs or modern sea scorpions, he said.

Previously, these spooky sea monsters were thought to be fearsome predators, devouring armored fishes and giant cephalopods (related to modern squids and nautiluses). Their compound eyes and large claws seemed to suggest as much.

But more recently, a study revealed that pterygotid claws wouldn't have been strong enough to break into armored fish or cephalopod shells.

In the recent study, Briggs and his team set out to examine the eyes of these ancient sea scorpions, to determine whether they had good enough vision to be great hunters.

Some of the lenses in the creatures' eyes were big enough for researchers to see them without any help from technology, but others had to be viewed under an electron microscope. The team estimated the angle between the lenses and the size of the lenses, comparing them with the eyes of a smaller eurypterid relative and of modern arthropods.

Briggs and his team concluded that the giant arthropods actually had poor eyesight. They probably lived near the bottom of the sea and likely hunted soft-bodied animals in dark waters or at night, Briggs said. But the fossil evidence limits these interpretations, so it's hard to know for sure how the animals behaved, he added.

After about 35 million years, pterygotids died out, and "it's a good thing they did," Brigg said. "They wouldn't be good company."

http://www.livescience.com/46708-ancient...sight.html
[Image: wildcat10-CougarHuntingDeer.jpg]
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