Paleonotology

Paleontologists at the �ؿ�ζSM and the Royal Ontario Museum have uncovered fossils of a large new predatory species in half-a-billion-year-old rocks from Kootenay National Park in the Canadian Rockies.

This new species has rake-like claws and a pineapple-slice-shaped mouth at the front of an enormous head, and it sheds light on the diversity of the earliest relatives of insects, crabs, spiders and their kin. The findings were announced a study published Wednesday in Proceedings of the Royal Society B.

Reaching up to a foot in length, the new species, named Cambroraster falcatus, comes from the famous 506-million-year-old Burgess Shale.

“Its size would have been even more impressive at the time it was alive, as most animals living during the Cambrian Period were smaller than your little finger,” said Joe Moysiuk, a PhD student in the department of ecology and evolutionary biology in the Faculty of Arts & Science and lead author of the study. He is based at the Royal Ontario Museum (ROM).

“Cambroraster was a distant cousin of the iconic Anomalocaris, the top predator living in the seas at that time, but it seems to have been feeding in a radically different way,” Moysiuk said.

PhD student Joe Moysiuk (left) and Associate Professor Jean-Bernard Caron working at the Burgess Shale in Kootenay National Park (photo courtesy of Joe Moysiuk)

The name Cambroraster refers to the remarkable claws of this animal, which bear a parallel series of outgrowths, looking like forward-directed rakes.

“We think Cambroraster may have used these claws to sift through sediment, trapping buried prey in the net-like array of hooked spines,” said Jean-Bernard Caron, an associate professor in the departments of Earth sciences and ecology and evolutionary biology. Caron is based at the ROM and is Moysiuk’s research supervisor.

With the space between the spines on the claws at typically less than a millimetre, this would have enabled Cambroraster to feed on very small organisms, although larger prey could also likely be captured, and ingested into the circular, tooth-lined mouth. This specialized mouth apparatus is the namesake of the extinct group Radiodonta, which includes both Cambroraster and Anomalocaris. Radiodonta is considered to be one of the earliest offshoots of the arthropod lineage, which today includes all animals with an exoskeleton, a segmented body and jointed limbs.

The second part of the species name – falcatus – was given in tribute to another of Cambroraster’s distinctive features: the large shield-like carapace covering its head, which is shaped like the Millennium Falcon spaceship from the Star Wars films.

“With its broad head carapace with deep notches accommodating the upward facing eyes, Cambroraster resembles modern living bottom-dwelling animals like horseshoe crabs. This represents a remarkable case of evolutionary convergence in these radiodonts,” Moysiuk said.

(Animation by Lars Fields/Royal Ontario Museum)

Such convergence is likely reflective of a similar environment and mode of life – like modern horseshoe crabs, Cambroraster may have used its carapace to plough through sediment as it fed.

Researchers were surprised by the large number of specimens recovered. “The sheer abundance of this animal is extraordinary,” said Caron, who is also the Richard M. Ivey Curator of Invertebrate Palaeontology at the ROM and leader of the field expeditions that unearthed the new fossils.

“Over the past few summers we found hundreds of specimens, sometimes with dozens of individuals covering single rock slabs.”

Based on more than 100 exceptionally well-preserved fossils now housed at the ROM, researchers were able to reconstruct Cambroraster in unprecedented detail, revealing characteristics that had not been seen before in related species.

“The radiodont fossil record is very sparse; typically, we only find scattered bits and pieces,” said Caron. “The large number of parts and unusually complete fossils preserved at the same place are a real coup, as they help us to better understand what these animals looked like and how they lived. We are really excited about this discovery.”

Fossils from the Cambrian Period, particularly from sites like the Burgess Shale, record a dramatic “explosion” of biodiversity at this time, culminating in the evolution of most of the major groups of animals that survive today. But, the story has far more intricacy than a straight line leading from simple ancestors to the vast diversity of modern species.

“Far from being primitive, radiodonts show us that at the very outset of complex ecosystems on Earth, early representatives of the arthropod lineage rapidly radiated to play a wide array of ecological roles,” said Moysiuk.

At left, the circular mouth apparatus of Cambroraster, showing rows of toothed plates. The right photo shows an isolated head carapace of Cambroraster, with deep notches that accommodated the eyes (photos courtesy of Jean-Bernard Caron)

The fossils were found at several sites in the Marble Canyon area in Kootenay National Park, B.C., which have been discovered by ROM-led field teams since 2012, with some of the key specimens unearthed just last summer. These sites are about 40 kilometres away from the original Burgess Shale fossil site in Yoho National Park that was first discovered in 1909. What is also exciting for researchers is the realization that there is a large new area in northern Kootenay National Park worth scientific exploration, holding the potential for the discovery of many more new species.

The Burgess Shale fossil sites are located within Yoho and Kootenay National Parks and are managed by Parks Canada.

The discovery and study of Cambroraster will be profiled in the upcoming episode of CBC’s The Nature of Things airing on Oct. 18, and on the free CBC Gem streaming service. These and other Burgess Shale specimens will be showcased in a new gallery at the ROM, the Willner Madge Gallery, Dawn of Life, expected to open in 2021. Starting this summer, select specimens of Cambroraster will be put on display in the New Research case within the current temporary Willner Madge Gallery, Dawn of Life preview exhibition.

Funding support for the research and fieldwork was provided by the Natural Sciences and Engineering Research Council of Canada, the Royal Ontario Museum, the National Geographic Society, the Swedish Research Council, the National Science Foundation and Pomona College. Moysiuk’s PhD research is also supported by an NSERC Canada Graduate Scholarship.

The story was written by the Royal Ontario Museum.

Where did animals with tail weapons go? U of T expert does the research

noreen.rasbach — Wed, 17 Jan 2018 20:53:02 +0000

Where did animals with tail weapons go? U of T expert does the research

noreen.rasbach Wed, 01/17/2018 - 15:53

Cutline

Illustration of ankylosaurus (De Agostini Picture Library/De Agostini/Getty Images)

Topic

Global Lens

Faculty of Arts & Science

Paleonotology

Research & Innovation

Why is it that many dinosaurs had formidable tail weapons – such as the ankylosaurus, with its clubbed tail, and the stegosaurus, with its spear-like spikes – but animals today do not?

Victoria Arbour, a paleontologist at the �ؿ�ζSM and the ROM, decided to figure out why. With Lindsay Zanno, a paleontologist from North Carolina State University, the researcher compiled data about nearly 300 mammals, reptiles, birds and dinosaurs, both extinct and living, looking for commonalities, according to a report in the New York Times.

The Times reports that the team identified three characteristics in land-dwelling mammals, reptiles and nonavian dinosaurs that may be linked with evolving bony tail weapons: being large (the size of a mountain goat or bigger), eating plants and already having an armoured body.

“That’s a really rare combination no matter what time period you’re looking at,” Arbour told the Times.

The research was published Wednesday in the Proceedings of the Royal Society B.

Many modern animals that use tails as weapons – like porcupines – have tails made of keratin, not bone. Modern lizards like iguanas, which can lash their tails, do not have spikes.

Read the full New York Times report

Read the research

This is your chance to see dinosaurs drawn by palaeontology illustrator from famed Reisz Lab

krisha — Wed, 13 Jul 2016 13:41:28 +0000

This is your chance to see dinosaurs drawn by palaeontology illustrator from famed Reisz Lab krisha Wed, 07/13/2016 - 09:41

Blake Eligh

Author legacy

Blake Eligh

Topic

As a child, Diane Scott struggled with reading – until a trip to the Etobicoke Bookmobile revealed that she had been reading the wrong books.

Told to choose anything she wanted, the seven-year-old skipped the standard children’s stories in favour of an illustrated guide to human diseases. The book proved to be the gateway to literacy for Scott. And the combination of science and images helped to set the course for a research career that has spanned nearly four decades.

Since 1979, Scott has worked as a researcher and graphic artist, documenting paleontological discoveries at The Reisz Lab at U of T Mississauga. A retrospective of her illustration work opened in May at Uof T Mississauga in the offices of the Master of Biomedical Communications program.

Exhibit curator and associate professor Dave Mazierski sifted through Scott’s considerable catalogue of work to find examples of her evolving style and unusual specimens.

“Most of the drawings have been published, but if you’re not involved in the research, you probably wouldn’t have seen these images,” Mazierski says, adding that three of Scott's earliest drawings had been taped to a window in the lab. “We wanted more people to see them and be aware that this work is being done here.”

Scott, who has no formal artistic training, earned her bachelor of science degree in 1980 at what was then Erindale College. Beginning as an undergraduate summer student, Scott soon demonstrated her unique talents for detailed technical work and accurate observational drawings.

“In this field, there are people who are artists and there are people who are technical preparators, but there’s only one Diane, who does both,” says renowned biology professor and long-time collaborator Robert Reisz. “I don’t know of anybody else who does what she does.”

As a lab technician, fossil preparator and scientific illustrator, Scott is an anomaly. “I take the project from the beginning—I prep it, figure it out, draw it and reconstruct it,” she says. “I’m not a PhD or a post-doc. It’s very unusual for someone with my background to be allowed to do the things I do.”

Scott and Reisz have worked together for 37 years in what both describe as a true partnership. Scott has dozens of publications and hundreds of citations to her credit. “It’s a scientific conversation between Diane and myself,” Reisz says. “When I have a perspective, I have to prove it to her and she challenges me constantly. I drive the research, but Diane is the one who executes and carries forward the work.”

Scott receives specimens from around the world, and often doesn’t know what she’s got until the preparatory work is completed. She uses a small pneumatic tool to chip away layers of sediment and reveal the fossil underneath. It’s painstaking work – Scott won’t work with anyone else in the room for fear of vibrations. She once spent six months slowly uncovering a clutch of small Massospondylus eggs and embryos trapped in rock. “The eggshell was thin as two pieces of paper and the embryonic bone was so fine that when you wet it, it disappeared,” she remembers. Over the years, she has developed a kind of sixth sense about what may lie beneath layers of sediment. “You almost get a sense of where the bones are,” she says. “It’s a fine line. You have to know when to stop.”

Once the specimen is prepared, Scott uses micromeasurements and her vast knowledge to reconstruct what the animal might have looked like. “You have to figure out where one bone stops and another begins. You have to look for clues to help identify what kind of an animal it is. Sometimes, it’s something new that we haven’t seen before,” she says. ”There’s no easy way of doing it.”

Scott then draws the specimen. In the early days, she used a camera lucida to create precise renderings of what she saw. Part drawing aid, part optical illusion, the camera lucida is a device that reflects the image of an object through a prism, allowing the artist to see the object and the drawing surface at the same time. Peering into the camera, Scott used a fine stippling technique, something she likens to drafting, to ensure clear reproductions. The camera lucida has been replaced by a scanning electron microscope and Photoshop software, but Scott still draws by hand. She uses Coquille board, a paper with a pebbled texture that picks up soft wax and graphite conté pencil to create the stippled effect so necessary for print reproduction. “It’s unforgiving and impossible to erase, but I love it because it’s artistic,” Scott says. With three decades of practice, she doesn’t often make mistakes.

“As an illustrator, I’ve been impressed with how remarkable and beautiful these drawings are,” Mazierski says. “You can see from one to the next how Diane’s technique has evolved. It’s lighter in tone and more precise and more refined.”

“She plays with light and the forms that light and shadow create to make the drawing clear, but she bends the rules where it suits her,” Mazierski continues. “She’s most concerned about the form.”

Scott’s enthusiasm for her work is infectious. She describes the Massospondylus eggs as “the cutest things!” and has a soft spot for a small, beaked hippo-like creature called a Dicynodont. “If this thing existed now, it would be the number one pet,” she says.

“I never had to grow up,” Scott says. “I’m always learning. I’m never bored. I always liked art and I liked science and I get to do both every day.”

Visitors can view the exhibit from Monday to Friday between 8:30 and 4:30 in the Biomedical Communications hallway on the third floor of the Health Sciences Complex at the �ؿ�ζSM Mississauga until September 30, 2016.