Skip to main content

Study: Spiders had ancient big-clawed relatives

By Steve Almasy and Elizabeth Landau, CNN
October 18, 2013 -- Updated 2152 GMT (0552 HKT)
Scientists used advanced imaging techniques to see the nervous system of the new Alalcomenaeus fossil specimen.
Scientists used advanced imaging techniques to see the nervous system of the new Alalcomenaeus fossil specimen.
STORY HIGHLIGHTS
  • The fossil is 520 million years old and was found in China
  • Using multiple images of the animal, the researchers discovered the nervous system
  • They also saw the brain was like those of today's spiders, scorpions
  • The work shows the early evolutionary differences, researcher says

(CNN) -- The ancient world was full of strange animals that have gone extinct, such as a group of marine species with claw-like structures emerging from their heads. A new study suggests that these creatures were related to spiders and scorpions.

Researchers discovered the fossilized remains of a species in southwest China that provides new insights into the evolution of animals in the modern era, scientists said. They report their findings in the journal Nature.

Scientists believe that the creature -- 1 inch long, and with two pairs of eyes -- lived 520 million years ago and that it crawled or swam in the ocean. They were able to reconstruct the creature's nervous system to gain insights about its evolutionary relationships to animals familiar to us.

"For the first time, we are able to use fossilised neural anatomy to sort out how fossil animals are related to animals today," study co-author Xiaoya Ma of the Department of Earth Sciences at the Natural History Museum in London wrote in an e-mail.

This creature belongs to the Alalcomenaeus genus, and its place in the animal kingdom lies in "a group of weird extinct animals" called the "megacheiran" or "great appendage" arthropods, Ma said.

The species of the Alalcomenaeus group had elongated, segmented bodies with about 12 pairs of appendages they used for swimming or crawling. They also had a pair of long, scissor-like head claws, most likely for grabbing or sensing.

Scientists say the reconstruction of the new creature's nervous system is the most complete for an arthropod living at that time, in the Cambrian geological period.

Discovery makes a splash: The rarest whale

The brain and central nervous system of the creature are organized in a way that is similar to those of the chelicerata, the group that includes horseshoe crabs and scorpions. This suggests a close evolutionary relationship between the ancient Alalcomenaeus and the living chelicerata.

A distinct group of arthropods called the mandibulates includes lobsters, insects, centipedes and millipedes.

Last year at the same site in China -- called the Chengjiang formation near Kunming -- Ma and colleagues discovered a 520 million-year-old crustacean-type nervous system in an animal called Fuxianhuia.

Taken together, these discoveries suggest that by 520 million years ago, the two major groups of arthropods had diverged. Their common ancestor must have been older, researchers said.

"This means the ancestors of spiders and their kin lived side by side with the ancestors of crustaceans," co-author Nick Strausfeld, neuroscience professor at the University of Arizona, said in a statement.

Strausfeld's team used sophisticated imaging techniques to look at the inch-long Alalcomenaeus fossil. One kind of scan revealed that iron had built up in the nervous system as the creature fossilized. They also used a technique called computed tomography that reconstructs 3-D features.

By combining these images and discarding any data that weren't in both, they were able to create a sort of negative X-ray photograph, "and out popped this beautiful nervous system in startling detail," Strausfeld said.

It confirmed what scientists had believed from the creature's outward appearance: The extinct genus Alalcomenaeus was related to chelicerates (spiders, scorpions and others).

They also saw that the brain in the fossil was like the brains found in modern scorpions and spiders.

If researchers find a fossil with features shared by this creature and the crustacean-like fossil Ma and colleagues found last year, that could be a common ancestor of both.

There's plenty more weirdness from ancient history to uncover.

18-foot oarfish discovered

ADVERTISEMENT
Part of complete coverage on
Science news
March 20, 2014 -- Updated 1412 GMT (2212 HKT)
For a Tyrannosaurus rex looking for a snack, nothing might have tasted quite like the "chicken from hell."
March 14, 2014 -- Updated 2229 GMT (0629 HKT)
Everyone is familiar with Tyrannosaurus rex, but humanity is only now meeting its much smaller Arctic cousin.
March 6, 2014 -- Updated 1712 GMT (0112 HKT)
At about 33 feet long, weighing 4 to 5 tons and baring large blade-shaped teeth, the dinosaur Torvosaurus gurneyi was a formidable creature.
February 21, 2014 -- Updated 1143 GMT (1943 HKT)
This Pachyrhinosaurus can go to the head of its class.
March 27, 2014 -- Updated 1204 GMT (2004 HKT)
Science is still trying to work out how exactly we reason through moral problems, and how we judge others on the morality of their actions. But patterns are emerging.
February 28, 2014 -- Updated 0006 GMT (0806 HKT)
A promising way to stop a deadly disease, or an uncomfortable step toward what one leading ethicist called eugenics?
February 15, 2014 -- Updated 0107 GMT (0907 HKT)
Seattle paleontologists safely removed the largest fossilized mammoth tusk discovered in the region from a construction site.
February 14, 2014 -- Updated 2137 GMT (0537 HKT)
For the first time, scientists have created human lungs in a lab -- an exciting step forward in regenerative medicine.
April 23, 2013 -- Updated 1013 GMT (1813 HKT)
A mysterious, circular structure, with a diameter greater than the length of a Boeing 747 jet, has been discovered submerged about 30 feet underneath the Sea of Galilee in Israel.
February 12, 2014 -- Updated 1255 GMT (2055 HKT)
Tiny rocket-shaped metal particles might one day take a wild ride inside your body.
February 6, 2014 -- Updated 2011 GMT (0411 HKT)
Ten years ago on New Year's Eve, Dennis Aabo Sorensen was launching fireworks when a defective rocket blew up. He was rushed to the hospital, and his left hand was amputated.
January 17, 2014 -- Updated 2225 GMT (0625 HKT)
Every corner of the planet offers some sort of natural peculiarity with an explanation that makes us wish we'd studied harder in junior high Earth science class.
January 9, 2014 -- Updated 1743 GMT (0143 HKT)
There is a light show in the ocean that you can't see, but many fish can. There's quite a display of neon greens, reds, and oranges going on underneath the surface.
December 15, 2013 -- Updated 0053 GMT (0853 HKT)
One trillionth of a second after the Big Bang is the timeframe that physicist Joe Incandela knows well.
November 26, 2013 -- Updated 1657 GMT (0057 HKT)
Scientists have uncovered archaeological evidence of when Buddha's monumentally influential life occurred.
November 14, 2013 -- Updated 1320 GMT (2120 HKT)
Deep in a remote, hot, dry patch of northwestern Australia lies one of the earliest detectable signs of life on the planet, tracing back nearly 3.5 billion years, scientists say.
November 3, 2013 -- Updated 1315 GMT (2115 HKT)
Four top environmental scientists raised the stakes Sunday in their fight to reverse climate change and save the planet.
October 18, 2013 -- Updated 2152 GMT (0552 HKT)
A new study suggests that a group of marine species with claw-like structures emerging from their heads were related to spiders and scorpions.
October 19, 2013 -- Updated 1604 GMT (0004 HKT)
The most complete early human skull has been found in the European country Georgia.
September 4, 2013 -- Updated 1910 GMT (0310 HKT)
We leave genetic traces of ourselves wherever we go -- in a strand of hair left on the subway or in saliva on the side of a glass at a cafe.
ADVERTISEMENT