Tag: Burgess Shale

Paleontology News for September 2021: A new large arthropod species discovered in the famous Burgess Shale. Plus a little pre-paleontology caused by Climate Change.

The main pursuit of paleontology is to learn the pathways by which Earth’s first creatures evolved into the species we see today, to study evolution in the field. In this month’s post I’ll be discussing stories that illustrate evolution from both the beginnings of multi-cellular life to observations of evolution in action today.

Of course the most familiar illustration of evolution is all about us! (Credit: History.com)

For most of life’s time here on Earth it consisted of nothing but single celled organisms. Then, about 600 million years ago the first simple multi-celled creatures came into being, creatures that have become known as the Ediacaran fauna. Because these first plants and animals had nothing in the way of hard parts however fossils of them are exceptionally rare and don’t reveal much about their anatomy.

The first multi-cellular living creatures had no hard parts so the fossil remains are very rare and don’t tell us a whole lot about the creatures. (Credit: Laidlaw Scholarships University of St. Andrews)

Animals with hard parts first appeared about 550 million years ago during the early Cambrian period and some of the best fossils from the Cambrian period are found in British Columbia in the world famous Burgess Shale and nearby fossil sites. The remarkable preservation of the fossils from the Burgess Shale is due to both the fine grained particles making up the shale as well as the fact that the animals that were fossilized seemed to have been buried intact in mudslides before their remains could be eaten by scavengers.

The most common fossil species found in the Burgess Shale is Marella splendens also known as the ‘Lace Crab’. This specimen is simply a beautiful fossil. (Credit: Smithsonian Institute)

As might be expected the creatures found in the Burgess Shale were mainly small, the size of a finger being rather common. After all multi-cellular life was brand new and it takes a while to go from being microscopic to the size of a human being let alone that of a whale.

Trilobites were amoung the largest and most advanced creatures during the Cambrian period. Today they would be considered small and primitive. (Credit: West Coast Traveler)

Size has its advantages however, particularly if you want to catch and eat other creatures. So it’s no surprise that the biggest animal yet discovered in the Burgess Shale, a creature known as Anomalocaris, was a predator about one meter in length. Despite its strangeness, the size of Anomalocaris made it the Tyrannosaurus rex of its day.

Considered the largest and fiercest predatory during the Cambrian, Anomalocaris was still only about a meter in length. (Credit: Wikipedia)

Now another large and equally strange creature has been discovered by paleontologists associated with the Royal Ontario Museum in an outcrop of shale near the Burgess Shale site in British Columbia and of the same age. Given the name Titanokorys gainesi the fossil belongs to a group of arthropods characterized by having a large, three part carapace covering most of their bodies that made them look almost like living heads.

With a head shield the covers more than half its body Titanokorys gainesi is related to Anomalocaris and appears to have lived by using it broad head as a plow to dig out food from the sand at the bottom of the ocean. (Credit: Sci-news.com)

T gainesi in particular had a broad, flat carapace about a half-meter in length along with multifaceted eyes and two spiny claws to grab food and bring it to a mouth shaped like a slice of pineapple. The paleontologists who described T gainesi speculate that the creature may have used its large carapace like a plow to stir up the muddy ocean bottom so that its claws could capture worms and other small animals.

As you might guess most of the fossil specimens of T gainesi discovered so far are of the creatures large head shield. (Credit: The Times of Israel)

T gainesi is yet another example of how, half a billion years ago evolution was experimenting to find solutions to the problems of how to survive in a hostile world. That same problem is still being faced by the life forms of today’s world but modern animals have the additional difficulty of having to adapt to a rapidly warming planet due to human induced climate change. In order to survive in this new environment Earth’s creatures must do what they have always done, adapt and evolve.

As usual Darwin got it right. It’s all about adapting! (Credit: Gihan Perera)

Now a new study by ornithologist Sara Ryding of Deakin University in Australia has described some of the changes that are already taking place in warm-blooded animals. Published in the journal ‘Trends in Ecology and Evolution’ the research details the anatomical changes, ‘shapeshifting’ that have been measured in a large number of bird and mammalian species.

The ancient myths about shapeshifters was all about adapting in order to survive. Maybe those ancient peoples weren’t as dumb as we think they were. (Credit: Deep Trance Now)

For example several species of Australian parrot have been found to be growing beaks that are 10% larger when compared to preserved specimens from 100 years ago. The same increase in beak size has also been found in North American dark-eyed juncos, a variety of songbird. In both cases the increase in bill size correlates positively with a measured increase in average temperature in the areas populated by the birds.

In order to better regulate their body temperature in a warming world Australian Parrots are growing bigger beaks! (Credit: ABC News)

In mammals such as wood mice and masked shrews a similar 10% increase has been measured in tail length and leg size. All of these adaptations have one thing in common, they provide the animal with a larger surface area to radiate heat and cool their body temperature. Again there is a clear connection for the larger body parts to rising temperatures in the animal’s habitat.

Several species of small mammals have also been discovered to be increasing the size of their tails and legs in order to increase surface area to aid in cooling their bodies in a warmer climate. (Credit: Wikipedia)

The fact that some species are evolving in response to global warming shouldn’t be taking as a sign that those animals are solving the problem of climate change however. As Doctor Ryding puts it, “shapeshifting does not mean that animals are coping with climate change and that all is ‘fine’. It just means that they are evolving to survive it. But we’re not sure what the other ecological consequences are, or indeed that all species are capable of changing and surviving.”

Those who cannot adapt become extinct, it’s as simple as that. The question then becomes, will we humans adapt to save our world or perish as a part of a new mass extinction? (Credit: National Geographic Society)

  Paleontologists have recognized at least six separate ‘mass extinctions’ in the fossil record. Some of these extinctions appear to have been caused by asteroid or comets impacting the Earth while others may have been due to massive volcanic eruptions. Right now our planet is experiencing another extinction event and there’s little doubt as to its cause, human beings!

Paleontologists discover possible oldest fossil intestines. These fossils could help show a path from the earliest multi-cellular life to the more familiar lifeforms of today.

Trying to understand the evolution of life on Earth is a bit like trying to figure out the picture on a jigsaw puzzle when you only have a dozen or so of the puzzle’s pieces. Obviously only a very few of the animals who ever lived have made fossils and of the few that have it’s usually only the hard part of the animal that fossilizes, bones and teeth for vertebrates, shells or exoskeletons for invertebrates. It’s a good question, how many species of animals with no hard parts existed in the past about whom we known absolutely nothing?

Fossils of Jellyfish are extremely rare because there’s almost nothing to fossilize. (Credit: Technology Networks)

The first multi-cellular animals, from about 600 million years ago, had no hard parts, and the very few impressions of them that paleontologists have found are so different from today’s species that it is hard to tell just what kind of animal they are. Known as the Ediacaran biota they have been described as quilt like, frond like or even balloon like in structure and whether or not they bare any relationship to the animals of today is a subject of hot debate. See images below.

Dicksonia costata is one of the stranger of the Ediacaran creatures. Is it even an animal? (Credit: Wikipedia)
Charnia is another Ediacaran creature. The fossil almost seems to indicate that the animal was quilted in structure. (Credit: Verisimilus at English Wikipedia)
Spriggina at least definitely looks like an animal that has a definite front and back and obviously moves in some fashion. (Credit: Pinterest)

Then, less than 60 million years later during the Cambrian period a very different assemblage of animals appeared as if from nowhere. These animals, best known from the famous Burgess shale fossils, are in most cases recognizable members of the modern major taxonomic groupings. The questions then arise, how did all these different groups arise at the same time, and what is their relation, if any, to the earlier Ediacaran animals.

The animals of the Cambrian, like this trilobite Olenoides, though strange are recognizably related to modern arthropods. (Credit: Trilobites.info)
Even the ‘wierd wonders’ of the Cambrian. like this artists impression of Opabinia, are still structured like modern animals. (Credit: Burgess Shale Science Foundation)

A recent discovery may provide the first definite link between an Ediacaran creature and a modern group of animals. As is happening more and more in paleontology the discovery wasn’t made by digging up a new fossil in the field but rather by looking at a fossil found years ago with a new instrument.

Tara Selly is a research assistant professor at the Department of Geological Sciences of the University of Missouri who was learning how to examine specimens using the university’s new X-ray microscope. For practice she grabbed a handy fossil, one that happened to come from Nye County in southern Nevada.

The fossil she chose was of a creature known as a cloudinomorph that dated to the end of the Ediacaran period, about 550 million years ago. Fossil cloudinomorphs are basically little tubes made of the material calcium carbonate and paleontologists have argued for years over whether the animal inside the tube was a relative of a coral medusa (technically an Anthozoan) or a tubeworm (Polychaete).

Cloudinomorphs were a well known but poorly understood Ediacaran fossil. (Credit: Tara Selly and James Schiffbauer)

When Doctor Selly looked at her cloudinomorph with the X-ray microscope she immediately saw a feature that was invisible under normal light, a tube running all the way through the fossil from one end to the other. If, as seemed likely, this tube was the intestine of the cloudinomorph that would immediate eliminate the possibility of the animals being related to a coral. You see corals and jellyfish have only one opening to their digestive system, which serves as both a mouth and an anus.

3D image of a cloudinomorph tube and the internal tube removed for inspection. The black line represents 2mm in length. (Credit: Tara Selly and James Schiffbauer)
Tara Selly shows grad student Brock Anderson how to prepare a specimen for viewing on the X-ray microscope. (Credit: Tara Selly and James Schiffbauer)

“A tube would tell us that it’s probably a worm,” according to James Schiffbauer the lead author of the study. “We can now say that their anatomical structure appears much more worm-like than coral-like.” If that is true is would establish the first firm link between an animal from the Ediacaran period and a modern group.

Possible reconstruction of the cloudinoporph animal. (Credit: New York Times)

In any case this is also the first evidence of any kind of complex internal structure, an internal organ of some kind inside an animal from the Ediacaran. That alone is important because it tells us that at least some of these early creatures were more than just balloons or quilts of undifferentiated cells. We may only have a few pieces of the jigsaw puzzle of life’s history but perhaps; thanks to Doctors Selly and Schiffbauer we may have just found a very important one.