Tag Archives: arthropod

Ancient 4-eyed, mega-clawed creature had spider brain

Ancient 4-eyed, mega-clawed creature had spider brain

By Denise Chow

Published October 17, 2013

LiveScience
  • mega-claw creature.jpg

    A close-up of the head region of the Alalcomenaeus fossil specimen with the superimposed colors of a microscopy technique revealing the distribution of chemical elements in the fossil. Copper shows up as blue, iron as magenta and the CT scans as green. The coincidence of iron and CT denote nervous system. The creature boasted two pairs of eyes (ball-shaped structures at the top). (N. STRAUSFELD/UNIVERSITY OF ARIZONA)

  • fossil-nervous-system

    This illustration shows the nervous systems of the Alalcomenaeus fossil (left), a larval horseshoe crab (middle) and a scorpion (right). Diagnostic features that reveal the evolutionary relationships among these animals include the forward posi (N. STRAUSFELD/UNIVERSITY OF ARIZONA)

The discovery of a fossilized brain in the preserved remains of an extinct “mega-clawed” creature has revealed an ancient nervous system that is remarkably similar to that of modern-day spiders and scorpions, according to a new study.

The fossilized Alalcomenaeus is a type of arthropod known as a megacheiran (Greek for “large claws”) that lived approximately 520 million years ago, during a period known as the Lower Cambrian. The creature was unearthed in the fossil-rich Chengjiang formation in southwest China.

Researchers studied the fossilized brain, the earliest known complete nervous system, and found similarities between the extinct creature’s nervous system and the nervous systems of several modern arthropods, which suggest they may be ancestrally related. [Photos of Clawed Arthropod & Other Strange Cambrian Creatures]

The arthropod family
Living arthropods are commonly separated into two major groups: chelicerates, which include spiders, horseshoe crabs and scorpions, and a group that includes insects, crustaceans and millipedes. The new findings shed light on the evolutionary processes that may have given rise to modern arthropods, and also provide clues about where these extinct mega-clawed creatures fit in the tree of life.

“We now know that the megacheirans had central nervous systems very similar to today’s horseshoe crabs and scorpions,” senior author Nicholas Strausfeld, a professor in the department of neuroscience at the University of Arizona in Tucson, said in a statement. “This means the ancestors of spiders and their kin lived side by side with the ancestors of crustaceans in the Lower Cambrian.”

The newly identified creature measures a little over an inch long (3 centimeters), and has a segmented body with about a dozen pairs of attached limbs that enabled it to swim or crawl.

“Up front, it has a long pair of appendages that have scissorlike components basically an elbow with scissors on the end,” Strausfeld told LiveScience. “These are really weird appendages, and there has been a long debate about what they are and what they correspond to in modern animals.”

Previously, researchers suggested megacheirans were related to chelicerates, since the extinct creature’s scissorlike claws and the fangs of spiders and scorpions have similar structures, said Greg Edgecombe, a researcher at the Natural History Museum in London, England.

“They both have an ‘elbow joint’ in the same place, and they both have a similar arrangement of a fixed and movable finger at the tip,” Edgecombe told LiveScience. “Because of these similarities, one of the main theories for what ‘great appendage arthropods’ are is that they were related to chelicerates. Thus, our findings from the nervous system gave an injection of new data to support an existing theory.”

Fossilized brain images
The researchers used CT scans to make 3D reconstructions of features of the fossilized nervous system. The scientists also used laser-scanning technology to map the distribution of chemical elements, such as iron and copper, in the specimen in order to outline different neural structures.

Though finding a well-preserved ancient nervous system is rare, the new study highlights the potential for similar discoveries, the researchers said.

“Finding ancient preservation of neural tissue allows us to analyzeextinct animals using the same tools we use for living animals,” Edgecombe said. “It suggests there should be more examples out there.”

About a year ago, Edgecombe and his colleagues found a different fossilized brain that revealed unexpected similarity to the brains of modern crustaceans.

“Our new find is exciting because it shows that mandibulates (to which crustaceans belong) and chelicerates were already present as two distinct evolutionary trajectories 520 million years ago, which means their common ancestor must have existed much deeper in time,” Strausfeld said in a statement. “We expect to find fossils of animals that have persisted from more ancient times, and I’m hopeful we will one day find the ancestral type of both the mandibulate and chelicerate nervous system ground patterns. They had to come from somewhere. Now the search is on.”

The detailed findings of the study were published online Wednesday in the journal Nature.

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More Real Monsters

This is an ongoing post that has proven popular.  You can type in “real monsters” in the Search box on the home page to find earlier posts.  I know monster is a relative term…

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500-million-year-old sea creature found

500-million-year-old sea creature found

By Tia Ghose

Published February 28, 2013

LiveScience

  • arthropod-fossil-2

    Scientists have unearthed a stunningly preserved arthropod, called a fuxhianhuiid, in a flipped position that reveals its feeding limbs and nervous system. (Yie Jang (Yunnan University))

Scientists have unearthed extraordinarily preserved fossils of a 520-million-year-old sea creature, one of the earliest animal fossils ever found, according to a new study.

The fossilized animal, an arthropod called a fuxhianhuiid, has primitive limbs under its head, as well as the earliest example of a nervous system that extended past the head. The primitive creature may have used the limbs to push food into its mouth as it crept across the seafloor. The limbs may shed light on the evolutionary history of arthropods, which include crustaceans and insects.

‘This is as early as we can currently see into arthropod limb development.’

– Javier Ortega-Hernández, an earth scientist at the University of Cambridge 

“Since biologists rely heavily on organization of head appendages to classify arthropod groups, such as insects and spiders, our study provides a crucial reference point for reconstructing the evolutionary history and relationships of the most diverse and abundant animals on Earth,” said study co-author Javier Ortega-Hernández, an earth scientist at the University of Cambridge, in a statement. “This is as early as we can currently see into arthropod limb development.”

The findings were published Wednesday, Feb. 27, in the journal Nature.

Primordial animal

The fuxhianhuiid lived nearly 50 million years before animals first emerged from the sea onto land, during the early part of the Cambrian explosion, when simple multicellular organisms rapidly evolved into complex sea life. [See Images of the Wacky Cambrian Creatures ]

While paleontologists have unearthed previous examples of a fuxhianhuiid before, the fossils were all found in the head-down position, with their delicate internal organs obscured by a large carapace or shell.

However, when Ortega-Hernández and his colleagues began excavating in a fossil-rich region of southwest China around Kunming called Xiaoshiba, they unearthed several specimens of fuxhianhuiid where the bodies had been flipped before fossilization. All told, the team unearthed an amazingly preserved arthropod, as well as eight additional specimens.

These primeval creatures probably spent most of their days crawling across the seabed trawling for food and may have also been able to swim short distances. The sea creatures, some of the earliest arthropods or jointed animals, probably evolved from worms with legs.

The discovery sheds light on how some of the earliest ancestors of today’s animals may have evolved.

“These fossils are our best window to see the most primitive state of animals as we know them – including us,” Ortega-Hernández said in a statement. “Before that there is no clear indication in the fossil record of whether something was an animal or a plant – but we are still filling in the details, of which this is an important one.”

Read more: http://www.foxnews.com/science/2013/02/28/500-million-year-old-sea-creature/?intcmp=obinsite#ixzz2NjmkstbB

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