How Silurian echinoderms ate


This October 2015 video from Utah State University in the USA is called What does the fossil record reveal about the evolution of Echinoderms?

By Laurel Hamers, 7:05pm, September 12, 2017:

Like sea stars, ancient echinoderms nibbled with tiny tube feet

Rare 430-million-year-old fossils preserve signs of these tentacle-like limbs

Sea stars and their relatives eat, breathe and scuttle around the seafloor with tiny tube feet. Now researchers have gotten their first-ever look at similar tentacle-like structures in an extinct group of these echinoderms.

It was suspected that the ancient marine invertebrates, called edrioasteroids, had tube feet. But a set of unusually well-preserved fossils from around 430 million years ago, described September 13 in Proceedings of the Royal Society B, provides proof.

Usually, when an echinoderm dies, “the tube feet are the first things that go,” says Colin Sumrall, a paleobiologist at the University of Tennessee, Knoxville who wasn’t part of the study. “The thing that’s so stunning is that they didn’t rot away.”

An abundance of soft-bodied creatures from the Silurian Period, which lasted from 443 to 416 million years ago, are preserved in a fossil bed in Herefordshire, England. The edrioasteroids found in this bed were probably buried alive by volcanic ash, entrapped before their soft tissues could break down, says study coauthor Derek Briggs, a paleontologist at Yale University. Decaying tissue then left a void that was filled in by minerals, which preserved the shape of the appendages.

Briggs and his collaborators slowly ground three fossils down, taking pictures layer-by-layer to build up a three-dimensional view. The specimens are a new genus and species, the analysis revealed. Unlike relatively flat sea stars and sand dollars, the species — dubbed Heropyrgus disterminus — had a conical body about 3 centimeters long. Its narrower end anchored in the seabed. The other end sported a set of five plates partially covering dozens of tube feet arranged in a pentagonal ring.

Today’s echinoderms use hydraulic pressure in a water vascular system to extend and retract their tube feet, which serve a variety of roles. The feet can help animals pull in tiny particles of food, filter water or gases, and even inch along the seafloor. Based on the placement of H. disterminus’s tube feet (and the fact that it’s stuck in one place), the animal probably used the appendages mostly for feeding and gas exchange, Briggs suggests. The fossils didn’t preserve the internal tubing that hooks up to the tube feet, but Briggs’ team thinks that it’s a series of canals arranged like spokes connected to a wheel hub.

Sumrall isn’t surprised that this edrioasteroid had tube feet. “It’s exactly what we would have expected,” he says. But all other preserved tube feet to date come from classes of echinoderms that still have living relatives today. Edrioasteroids are less closely related to modern echinoderms, so this find broadens the range of species that scientists know sported the structures.

H. disterminus does have a few surprises, though: Its tube feet are found in two sets, in an arrangement not seen in any other echinoderms. And while it has five-point symmetry in its fleshy top part (like most other echinoderms), that transitions to eight-point symmetry in its long, columnar body.

Sea stars sighted predators 79 million years ago: here.

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Ancient sea scorpions’ tails, weapons?


EN GARDE! Ancient sea scorpions (one illustrated, attacking an archaic fish) may have used serrated, swordlike tails for swimming or as weaponry. Picture by NATHAN ROGERS

From Science News:

Sea scorpions slashed victims with swordlike tails

New fossil suggests the body part was used for fighting, swimming

By Helen Thompson

11:00am, May 30, 2017

Ancient sea scorpions were hacks.

Some of the marine creatures had a thin, serrated spine on the tip of their tail — and that tail was surprisingly flexible, based on a 430-million-year-old fossil found in Scotland. Slimonia acuminata may have had the range of motion to strike large predators and prey, researchers report online April 18 in American Naturalist.

Scientists had thought that the ancient animals largely used their tails for swimming, primarily flapping them up and down like today’s lobsters and shrimp do and, to a limited degree, side to side like a rudder. But the tail on the new, well-preserved fossil curls dramatically to the side — a flexibility not seen in other sea scorpion specimens.

That bendiness suggests a purpose beyond propulsion, say study authors W. Scott Persons, a paleontologist, and John Acorn, an entomologist, both at the University of Alberta in Canada. The tail could have twisted around horizontally to strike a victim or dispatch a foe with the pointy end, and the saw-edged weapon would have encountered little water resistance.

Sea scorpions may have even pinned down prey with their front limbs while delivering lethal blows with their tails. Because S. acuminata appears quite early in sea scorpion evolution, slicing and dicing may have been the norm early on for the ancient critters, the researchers write.

Sea lily fossils discovery in World War I trenches


This 2015 video from the USA is called Everything About Crinoids

From Ohio State University in the USA:

Rock exposed in World War I trenches offers new fossil find

Sea lily ancestors spent youth hitchhiking around ancient oceans, discovery suggests

April 3, 2017

Summary: An unusual fossil find is giving scientists new ideas about how some of the earliest animals on Earth came to dominate the world’s oceans.

An international research team found 425-million-year-old fossilized remnants of juvenile crinoids, a distant ancestor of today’s sea lilies, encased in iron oxide and limestone in the Austrian Alps.

Researchers collected the rock from a formation on the border between Italy and Austria known as the Cardiola Formation, which was exposed in trenches dug during World War I.

Crinoids were abundant long ago, when they carpeted the sea floor. Most stalked crinoid fossils depict spindly, plantlike animals anchored to sea floor rocks, explained William Ausich, professor of earth sciences at The Ohio State University and co-author of the study in the open-access journal Geologica Acta.

Fossils of juvenile crinoids are rare, he said.

Rarer still is that these newly uncovered crinoids weren’t attached to rocks when they died. Whatever they were attached to during their young lives didn’t survive fossilization.

“The fossils indicate that they were either attached to objects floating in the water at the time, or attached to another bottom dweller that lacked preservable hard parts,” said Ausich said.

They might have clung to free-floating algae beds or swimming cephalopods, either of which could have carried them far away from where they formed as larvae.

Modern sea lilies reproduce by ejecting sperm and eggs into the water. Larvae grow into free-floating juvenile animals and eventually attach to the ocean bottom, where they grow to adulthood within 18 months.

At least, that’s what sea lilies do today. This fossil find suggests that their distant ancestors sometimes settled on objects that carried them far from home before they reached reproductive age.

“We now have important information about the behavior of these ancient organisms, and a clue as to why they had such a wide geographic distribution,” Ausich said.

With long, stem-like bodies topped with feathery fronds, crinoids resembled flowers, though the center of the “flower” was a mouth, and the “petals” were arms that captured plankton for food. At the other end of the creature was star-shaped organ called a holdfast, which gripped the seafloor.

While some of today’s sea lilies are able to detach their holdfasts from the seafloor and walk short distances on their arms, they don’t do it often. If their crinoid ancestors spent their entire adult lives similarly anchored to one spot, they couldn’t have spread worldwide without help.

Fossilized holdfasts are all that remain of the young crinoids uncovered in the Alps, and that’s not unusual, Ausich said.

“The hard part about studying the fossils that I study is that they need to be buried alive in order to be completely preserved,” he explained. “Crinoids and other echinoderms have a skeleton comprised of innumerable individual calcite plates held together by various connective soft tissues. These tissues begin to decompose within a day of an organism’s death.

“So, having only parts [of crinoids] rather than whole organisms is actually the norm — as frustrating as that may be.”

The sediment that eventually covered these young crinoids must have been rich in iron, because the holdfasts were preserved as minerals of iron oxide — and that detail is unusual, he added.

Today, the fossil holdfasts look like rusty star-shaped rings. The stars measure only 1 to 4 millimeters across, meaning they came from very young, post-larval juveniles.

The tiny fossils might have been hard to isolate from the surrounding rock, but researchers were able to take advantage of the presence of iron oxide to dissolve the limestone and pull the fossils from the resulting slurry with a magnet.

Researchers had actually collected rock samples from the Cardiola Formation long ago, Ausich said. The area contains abundant fossils, including ancient corals and trilobites. But only recently did anyone discover that these particular rock samples also contained the crinoid holdfasts.

Researchers are interested in crinoids not just because they’re part of Earth’s history, but because the various crinoid species were able to survive millions of years of climate changes to become the sea lilies we know today.

Ancient crustacean fossil named after David Attenborough


This 21 March 2017 video from England is called Cascolus ravitis, a 430 Million-Year-Old ‘Exceptionally Preserved’ Fossil.

From the University of Leicester in England:

430 million-year-old fossil named in honor of Sir David Attenborough

Ancient relative of the lobsters and crabs complete with soft-parts is new to science

March 22, 2017

Summary: A new 430 million-year-old fossil has been discovered by scientists, and has been named in honor of Sir David Attenborough. The discovery is a unique example of its kind in the fossil record, say the authors of a new report.

An international team of scientists led by the University of Leicester has discovered a new 430 million-year-old fossil and has named it in honour of Sir David Attenborough — who grew up on the University campus.

The fossil is described as ‘exceptionally well preserved in three-dimensions’ — complete with the soft-parts of the animal, such as legs, eyes and very delicate antennae. The fossil has been determined as an ancient crustacean new to science — a distant relative of the living lobsters, shrimps and crabs. There are about 40,000 crustacean species known today.

The find comes from volcanic ash deposits that accumulated in a marine setting in what is now Herefordshire in the Welsh Borderland.

Professor David Siveter of the Department of Geology at the University of Leicester made the discovery working alongside researchers from the Universities of Oxford, Imperial College London and Yale, USA.

Professor Siveter said: “Such a well-preserved fossil is exciting, and this particular one is a unique example of its kind in the fossil record, and so we can establish it as a new species of a new genus.”

“Even though it is relatively small, at just nine millimetres long, it preserves incredible detail including body parts that are normally not fossilized. It provides scientists with important, novel insights into the evolution of the body plan, the limbs and possible respiratory-circulatory physiology of a primitive member of one of the major groups of Crustacea.”

The fossil is named Cascolus ravitis in honour of Sir David, who grew up on University College Leicester campus (the forerunner of the University), in celebration of his 90th birthday. Cascolus is derived from castrum meaning ‘stronghold’ and colus, ‘dwelling in’, alluding to the Old English source for the surname Attenborough; while ‘ravitis” is a combination of Ratae — the Roman name for Leicester — ‘vita’, life, and ‘commeatis’, a messenger.

Professor Siveter said: “In my youth, David Attenborough‘s early programmes on the BBC, such as ‘Zoo Quest‘, greatly encouraged my interest in Natural History and it is a pleasure to honour him in this way.”

Sir David Attenborough said: “The biggest compliment that a biologist or palaeontologist can pay to another one is to name a fossil in his honour and I take this as a very great compliment. I was once a scientist so I’m very honoured and flattered that the Professor should say such nice things about me now.”

Professor Siveter added: “The animal lived in the Silurian period of geological time. Some 430 million years ago much of southern Britain was positioned in warm southerly subtropical latitudes, quite close to a large ancient continent of what we now call North America, and was covered by a shallow sea. The crustacean and other animals living there died and were preserved when a fine volcanic ash rained down upon them.”

The fossil specimen has been reconstructed as a virtual fossil by 3D computer modeling.

New frog from the Peruvian Andes is the first amphibian named after Sir David Attenborough: here.

Ancient placoderm fish, new discovery


A 423-million-year-old armored fish from China had jaws that resemble those of modern land vertebrates and bony fish. Picture by Dinghua Yang

From Science News:

Ancient armored fish revises early history of jaws

Placoderm fossil had skull bones like those of many modern vertebrates

By Meghan Rosen

2:00pm, October 20, 2016

A freaky fish with a head like a dolphin and a body like a tank may be to thank for human jaws.

The discovery of a 423-million-year-old armored fish from China suggests that the jaws of all modern land vertebrates and bony fish originated in a bizarre group of animals called placoderms, researchers report in the Oct. 21 Science.

Along with a different placoderm fossil from 2013, the new find, named Qilinyu rostrata, is helping rewrite the story of early vertebrate evolution, says paleontologist John Maisey of the American Museum of Natural History in New York City, who was not involved with the work.

“We’ve suddenly realized we had it all wrong,” he says.

The jaws of humans — and dogs, salmon, lizards and all other bony vertebrates — contain three key bones: the maxilla and premaxilla of the upper jaw, and the dentary of the lower jaw.

“Anything from a human being to a cod has recognizably the same set of bones in the head,” says study coauthor Per Ahlberg, a paleontologist at Uppsala University in Sweden. The big question, he says, is “Where did these bony jaws come from?”

More than a hundred million years before dinosaurs walked the Earth, fishes called placoderms thrived under water. Scientists knew that these armored fishes were early jawed animals, but their jaws were unusual:  “They look like sheet metal cutters,” Ahlberg says. “They’re these horrible bony blades that slice together.”

The blades, called gnathal plates, looked so peculiar that most scientists thought that the three-part jaw of humans originated in an early bony fish and that placoderms were just a funny little side branch in the vertebrate family tree. “The established view is that placoderms had evolved independently and that our jaw bones must have a separate origin,” Ahlberg says.

Placoderms are a highly debated group of animals, says paleontologist Martin Brazeau of Imperial College London. No one quite knew where to place them.

In 2013, Ahlberg and colleagues found a new clue in a 419-million-year old fossil that had the body of a placoderm, but the three-part jaw of a bony fish. Such an animal, called Entelognathus primordialis, “could never have been predicted from the fossil record,” says paleontologist Gavin Young of Australian National University in Canberra.

That work bolstered the idea that placoderms weren’t, in fact, their own odd group that dead-ended hundreds of millions of years ago — some were actually the ancestors of bony fish (and thus humans). But it was just one fossil, Ahlberg notes. “You don’t want to draw too big of conclusions from one animal.”

Two animals, though, is a different story. Qilinyu, the new fossil Ahlberg and colleagues describe, had an armored skull and trunk and was probably about the length of a box of tissues. Like Entelognathus, Qilinyu has a three-part, bony fish–like jaw, though the creature looks a bit more like a typical placoderm, Ahlberg says. The two fossils “form almost perfect intermediates” between placoderms and bony fishes, he says. Ahlberg and his colleagues suspect the key jaw elements of bony fish (and all land vertebrates) evolved from those bony blades of placoderms.

“This is part of our own early evolutionary history,” Ahlberg says. “It shows where our own jaws came from.”

Maisey puts it another way: “We are all fundamentally placoderms.”

See also here.

Fungus, oldest land fossil, discovered


This video says about itself:

Life on Earth began in Scotland… with 440mn year old fungus, scientists discover

2 March 2016

University of Cambridge scientists have discovered the origins of land-based life on the Scottish Hebridean Island of Kerrera, in the form of a primitive fungus.

Tortotubus fungus, also found in Gotland, Sweden, is said to be one of the first organisms to make its way from the sea on to land.

By Helen Briggs, BBC News in Britain:

‘Humble little fungus’ is oldest known land fossil

2 March 2016

It is smaller than a human hair, resembles a mushroom, and is thought to be the earliest fossil of a land-dwelling organism.

The fungus, which dates back 440 million years, spent its life under the ground rotting down matter.

Even the scientist who analysed it – Dr Martin Smith – admits it is a ”humble little fungus”.

But the pioneer, known as Tortotubus, could help explain how early life colonised the rocky barren Earth.

Most scientists agree that life moved from the sea to the land between 500 and 450 million years ago.

But in order for plants and animals to gain a foothold on terra firma there needed to be nutrients and soil to support them.

Fungi kick-started this process, by getting nitrogen and oxygen into the rudimentary soil.

Fossil record

Dr Smith says there were probably bacteria and algae already on land – but these are rarely preserved in the fossil record.

This makes Tortotubus probably the oldest fossil of a land-dwelling organism yet to be found.

Dr Smith told BBC News: ”It’s the first fossil of an organism that only lived on land.

”It would have broken down dead, decayed material – essentially rotted it.”

Mushroom-forming fungi

The fossilised fungus has been found in many locations, including Sweden and Scotland.

Each microfossil is shorter than a human hair is wide and has a rope-like structure similar to that of some modern-day fungi.

Scientists think that early fungi contributed to soil formation and the rotting process, thereby paving the way for flowering plants and trees,

The early land plants were not yet flowering plants or trees. These came much later.

then animals.

”During the period when this organism existed, life was almost entirely restricted to the oceans: nothing more complex than simple mossy and lichen-like plants had yet evolved on the land,” said Dr Smith, who carried out the research at the University of Cambridge but is now based at Durham University.

”But before there could be flowering plants or trees, or the animals that depend on them, the processes of rot and soil formation needed to be established.”

The research is published in the Botanical Journal of the Linnean Society.

See also here.

Huge fish discovered from long before dinosaurs


This video is called Fish of the Silurian Period.

By Jennifer Viegas:

Did Super-Sized Animals Live Long Before Dinosaurs?

June 12, 2014 11:00 AM ET

It’s generally believed that Earth’s earliest animals were not very big, but discovery of a huge new fish that lived around 423 million years ago has scientists rethinking what life was like close to 200 million years before the first dinosaurs emerged.

The fish, named Big Mouth Blunt Tooth (Megamastax amblyodus), is described in the latest issue of Scientific Reports. For its time, the toothy and lobe-finned fish was in the number one spot on the food chain.

“At 1 meter (3.3 feet) in length or greater, it was vastly larger than any other animal,” lead author Brian Choo told Discovery News, adding that Big Mouth was “likely the earliest vertebrate (backboned) apex predator in the fossil record.”

Choo, a paleontologist at the Chinese Academy of Sciences and Flinders University, and his colleagues analyzed Big Mouth’s remains, which were unearthed at the Kuanti Formation in Yunnan, southwestern China. During the fish‘s lifetime, a period known as the Silurian, this region was part of the South China Sea. It is where the marine ancestors of all jawed animals, including humans, first evolved.

Equipped with both piercing and crushing teeth, Big Mouth likely preyed upon hard-shelled moving species, such as mollusks and armored fishes. The second largest animal at the time, Guiyu onerios — aka Ghost Fish, was a mere one-third of Big Mouth’s size.

Why then was Big Mouth so big?

One reason, according to the researchers, is that competition among fish appears to have been fierce.

Co-author Min Zhu explained, “During the Silurian period, the South China Sea, then at the equator, was the cradle of early jawed vertebrates, thus the ecological competition among these creatures was very intense.”

Another reason is that Big Mouth probably had plenty of oxygen. Modern fish are generally worse off in low oxygen conditions, and big fish require more oxygen than small ones, Choo said. Big Mouth therefore could not have existed unless sufficient oxygen was present.

See also here.