Brachiopod fossils, clue to Cambrian climate


This 2008 video says about itself:

Invertebrate Fossils – Lesson 16 – Part 2 of 7

Horn coral
Brachiopod shells with external spines
• Seasonal growth of coral
Cambrian fauna
• Precambrian Ediacara fauna Australia – First fossils formed with many cells

From the University of Leicester in England:

Tiny fossils unlock clues to Earth’s climate half a billion years ago

May 9, 2018

An international collaboration of scientists, led by the University of Leicester, has investigated Earth’s climate over half a billion years ago by combining climate models and chemical analyses of fossil shells about 1mm long.

The research, published in Science Advances, suggests that early animals diversified within a climate similar to that in which the dinosaurs lived.

This interval in time is known for the ‘Cambrian explosion‘, the time during which representatives of most of the major animal groups first appear in the fossil record. These include the first animals to produce shells, and it is these shelly fossils that the scientists used.

Scientists have long thought that the early Cambrian Period was probably a greenhouse interval in Earth’s climate history, a time when there were no permanent polar ice sheets.

Until now, however, scientists have only had a sense of what the Cambrian climate was like because of the types of rock that were deposited at this time — while it has long been believed that the climate was warm, specific details have largely remained a mystery.

Data from the tiny fossil shells, and data from new climate model runs, show that high latitude (~65 °S) sea temperatures were in excess of 20 °C. This seems very hot, but it is similar to more recent, better understood, greenhouse climates like that of the Late Cretaceous Period.

Thomas Hearing, a PhD student from the University of Leicester’s School of Geography, Geology and the Environment, explained: “Because scientists cannot directly measure sea temperatures from half a billion years ago, they have to use proxy data — these are measurable quantities that respond in a predictable way to changing climate variables like temperature. In this study, we used oxygen isotope ratios, which is a commonly used palaeothermometer.

“We then used acid to extract fossils about 1mm long from blocks of limestone from Shropshire, UK, dated to between 515 — 510 million years old. Careful examination of these tiny fossils revealed that some of them have exceptionally well-preserved shell chemistry which has not changed since they grew on the Cambrian sea floor.”

Dr Tom Harvey, from the School of Geography, Geology and the Environment, added: “Many marine animals incorporate chemical traces of seawater into their shells as they grow. That chemical signature is often lost over geological time, so it’s remarkable that we can identify it in such ancient fossils.”

Analyses of the oxygen isotopes of these fossils suggested very warm temperatures for high latitude seas (~65 °S), probably between 20 °C to 25 °C.

To see if these were feasible sea temperatures, the scientists then ran climate model simulations for the early Cambrian. The climate model simulations also suggest that Earth’s climate was in a ‘typical’ greenhouse state, with temperatures similar to more recent, and better understood, greenhouse intervals in Earth’s climate history, like the late Mesozoic and early Cenozoic eras.

Ultimately, these findings help to expand our knowledge of the early animals of the period and the environment in which they lived.

Thomas Hearing said: “We hope that this approach can be used by other researchers to build up a clearer picture of ancient climates where conventional climate proxy data are not available.”

The research was carried out as an international collaboration involving scientists from the University of Leicester (UK), British Geological Survey (BGS; UK), and CEREGE (France). This collaboration brought together expertise in geochemistry, palaeontology and climate modelling to tackle this longstanding problem.

The scientists have co-authored an open access (publicly available) paper in the journal Science Advances.

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Leafcutter ants, new research


This 2015 video is called Leafcutter Ants‘ Life.

From Rice University in the USA:

Leafcutter ants‘ success due to more than crop selection

Genetic analysis finds leafcutter ants originated in South America

May 9, 2018

A complex genetic analysis has biologists re-evaluating some long-held beliefs about the way societies evolved following the invention of agriculture — by six-legged farmers.

Like humans, leafcutter ants grow crops, and like humans, farming allows the ants to produce enough food to support millions of individuals who work at specialized jobs. But while people invented agriculture at the dawn of civilization about 10,000 years ago, leafcutters began cultivating massive subterranean fungus gardens more than 10 million years ago.

In a study published this week in Molecular Ecology, biologists from Rice University, the University of Texas at Austin (UT Austin) and Brazil’s São Paulo State University analyzed genetic data from samples collected at leafcutter nests throughout South, Central and North America and concluded that the ants originated in South America and owe their success to something more than their choice of crops.

The ability to grow domesticated crops was a major turning point in human history and evolution, and we thought, until recently, that a similar thing was true for leafcutters,” said study co-author Scott Solomon, an evolutionary biologist at Rice who collected many of the study’s samples as a graduate student and postdoctoral researcher at UT Austin and the Smithsonian Institution in Washington, D.C. “Our findings suggest that several of the things we thought we ‘knew’ about leafcutters are not true.”

The research, led by co-author Ulrich Mueller, Solomon’s longtime UT collaborator and mentor, is available in both the newly published paper and a 2017 companion study, also published in Molecular Ecology.

“This study started 20 years ago as a collaboration between Brazilian and Texan labs and developed into a huge collaboration involving 22 labs surveying leafcutter ants in 17 countries,” said Mueller, the William Morton Wheeler-Lost Pines Professor in UT Austin’s Department of Integrative Biology. “Because of this international effort, we now have a comprehensive understanding of leafcutter ecology and evolution.”

Leafcutter ants are found only in the Americas. More than 40 species range from Argentina to the southern United States, and they are a dominant ecological player in any forest or grassland they inhabit.

“They aren’t the only ants that grow fungi, but if you compare leafcutter ants with other ants that grow fungi, there are many differences,” Mueller said. “For starters, no other ants use freshly cut leaves to grow their fungi.”

Ants that grow fungus on dead and decaying leaves have been around even longer than leafcutters, probably about 50 million years, Solomon said. But leafcutters’ ability to use living leaves was a quantum leap in evolutionary terms because it opened up the entire ecosystem. For example, Solomon said, the ability to consume plant matter they cannot directly digest allows a nest of leafcutters to consume about as much vegetation each year as a full-grown cow.

“Once you can use fresh leaves, it gives you access to so much more food,” Solomon said. “If you can grow and raise your crop on any leaf that’s growing out there, then the sky’s the limit.”

In comparison with other fungus-growing ants, leafcutter colonies are enormous, Solomon said. “They’re on the order of millions of individuals. Some leafcutter colonies are so large that they show up on photos taken by satellites in space.”

Leafcutters also have specialized tasks. Individual worker ants come in different sizes, and they have different jobs.

“Some are specialized on raising the young,” Solomon said. “Others are specialized on removing weeds and disease inside the nest. Others are specialized on going out and finding food, and yet others are specialized on defending the colony.

“All of the specialization is unique to the leafcutters,” he said. “With other fungus-growing ants, the workers are basically interchangeable. They don’t have these specialized tasks.

“One of the long-held truths of our field was that leafcutters grow a special and unique kind of fungus that no other ant could grow,” Solomon said. “It was thought that something about that unique crop allowed them to do these things that other fungus-growing ants couldn’t do.”

The new studies, which are the first to analyze the genes of fungi from hundreds of leafcutter colonies across the Americas, found instances where other ants grew the specialized “leafcutter-only” fungus, as well as instances where leafcutters grew more generic fungal crops.

“It’s not the crop that makes them special,” Mueller said. “We found that leafcutter ants and their fungi have co-evolved, and while that’s not a surprise, the evidence suggests that this co-evolution occurred in a more complex way than previously believed.

“For example, we found that the type of fungi that was long thought to be unique to leafcutters can be grown by other ants on dead plant material,” he said. “In one case, it’ll be grown on fresh vegetation, and in another case, it won’t.”

Solomon said, “The question is what gives this fungus the ability to digest freshly cut leaves? It’s not something that is inherent in the fungus. There seems to be something about the way the leafcutter ants are cultivating the fungus that gives it that ability.”

Solomon began collecting leaf-cutting ants and their fungi in Central America in 2002 as a graduate student in Mueller’s lab. In 2007 Solomon expanded his work, thanks to a National Science Foundation (NSF) international postdoctoral fellowship that allowed him to spend a year working with study co-author Mauricio Bacci Jr. at São Paulo State University in Rio Claro, Brazil. Solomon’s samples and dozens of others gathered over the years by Mueller’s and Bacci’s teams allowed the researchers to pinpoint the origin of leafcutters to South America, probably in the grassland plains of what is now southern Brazil and Argentina, Solomon said.

“We sampled tons of different nests of leafcutter ant species throughout the entire range of all leafcutters, which goes from Texas in the extreme north down to Argentina,” Solomon said. “What’s novel about our approach is how much sampling there was, particularly in South America. In the past, there has been a lot of sampling, but it was focused in just a few different regions, particularly in Costa Rica and Panama.

“It turns out the leafcutters in those places don’t represent species that live elsewhere,” he said. “By going and sampling in other places, especially in the open grasslands of southern Brazil, Paraguay and northern Argentina, we were able to show that the greatest genetic diversity of leafcutter fungi is in South America. Usually, wherever there’s the greatest genetic diversity is where a group originated. That is true for humans, and that’s just generally true of other species, and that leads us to believe the leafcutters originated in the grasslands of South America.”

Mueller said, “The study illustrates the importance in science of re-evaluating entrenched assumptions, amassing large data sets and collaborating internationally before reaching conclusions.”

Ants working together to carry a large piece of food get around obstacles by switching between two types of motion: one that favors squeezing the morsel through a hole and another to seek a path around the barrier: here.

Scarlet lily beetles mate on flowering plant


This 8 May 2018 video shows scarlet lily beetles mating on a snake’s head fritillary flowering plant.

Wim Bender in the Netherlands made this video.

Five ‘fish’ that aren’t fish


This 2018 video says about itself:

In this short video, underwater cinematographer Jonathan Bird explains what traits make a fish a fish, and 5 top animals often called fish that actually are not fish like the jellyfish, starfish, cuttlefish, crayfish and Swedish Fish!

Green-veined white butterflies mating


This late April 2018 video shows two green-veined white butterflies mating.

Ria Pereboom made this video in Heerjansdam in the Netherlands.

Rapid evolution fails to save butterflies from extinction in face of human-induced change: here.

Precambrian animals, new research


This video from the USA says about itself:

The Ediacara biota and first mass extinction of metazoan life

5 February 2016

Just what are prehistoric aliens? Simon Darroch from the Department of Paleobiology [of the Smithsonian’s National Museum of Natural History] introduces us to the Ediacaran biota of Southern Namibia.

From the University of California – Riverside in the USA:

Ediacara Biota flourished in bacterially rich marine habitats

May 4, 2018

Summary: Researchers have used biomarkers in ancient rocks to learn more about the environmental conditions and food sources that sustained the Ediacara Biota.

Some of the earliest animals on Earth were soft-bodied ocean-dwellers that ranged from a few inches to several feet and were shaped like circular discs, tubes, or cushion-like bags.

While fossil impressions from the Ediacaran Era — 635 to 541 million years ago — reveal their existence, little is known about this fascinating group of animal-like creatures, which preceded more complex animals with skeletons.

In a paper published Friday, May 4, in Nature Communications, researchers at the University of California, Riverside, used biomarkers in ancient rocks to learn more about the environmental conditions and food sources that sustained this group of animals, called the Ediacara Biota. Led by Gordon Love, a professor of biogeochemistry at UCR, the team studied molecular fossils, known as lipid biomarkers, made by the ancient biological communities and preserved within sedimentary rocks that contain early animal fossils. The communities they studied lived off the coast of the ancient continent Baltica — encompassing modern day Russia, Ukraine and the Baltic States — between 560 to 540 million years ago.

Love said the Ediacara Biota lived in nutrient-poor regions of the sea on the continental shelf, an extension of land under the ocean that results in relatively shallow water. Despite this oligotrophic environment, the researchers found there were sufficient nutrients and organic debris for feeding sustained by bacterial primary production and dissolved organic matter.

The team also observed a dearth of sponge biomarkers, suggesting possible niche competition between the Ediacara Biota and sponges in different marine settings.

“Different environmental conditions and nutritional resources could have selected for very different community structures in different regions of the Ediacaran oceans,” Love said.

Sea slug uses solar energy


This 2016 video from Britain is called The Solar Powered Sea Slug (Elysia viridis).

From Rutgers University in the USA, about an American relative of that species:

Solar powered sea slugs shed light on search for perpetual green energy

Near-shore animal becomes plant-like after pilfering tiny solar panels and storing them in its gut

May 3, 2018

In an amazing achievement akin to adding solar panels to your body, a Northeast sea slug sucks raw materials from algae to provide its lifetime supply of solar-powered energy, according to a study by Rutgers University-New Brunswick and other scientists.

“It’s a remarkable feat because it’s highly unusual for an animal to behave like a plant and survive solely on photosynthesis“, said Debashish Bhattacharya, senior author of the study and distinguished professor in the Department of Biochemistry and Microbiology at Rutgers-New Brunswick. “The broader implication is in the field of artificial photosynthesis. That is, if we can figure out how the slug maintains stolen, isolated plastids to fix carbon without the plant nucleus, then maybe we can also harness isolated plastids for eternity as green machines to create bioproducts or energy. The existing paradigm is that to make green energy, we need the plant or alga to run the photosynthetic organelle, but the slug shows us that this does not have to be the case.”

The sea slug Elysia chlorotica, a mollusk that can grow to more than 2 inches long, has been found in the intertidal zone between Nova Scotia, Canada, and Martha’s Vineyard, Massachusetts, as well as in Florida. Juvenile sea slugs eat the nontoxic brown alga Vaucheria litorea and become photosynthetic — or solar-powered — after stealing millions of algal plastids, which are like tiny solar panels, and storing them in their gut lining, according to the study published online in the journal Molecular Biology and Evolution.

Photosynthesis is when algae and plants use sunlight to create chemical energy (sugars) from carbon dioxide and water. The brown alga’s plastids are photosynthetic organelles (like the organs in animals and people) with chlorophyll, a green pigment that absorbs light.

This particular alga is an ideal food source because it does not have walls between adjoining cells in its body and is essentially a long tube loaded with nuclei and plastids, Bhattacharya said. “When the sea slug makes a hole in the outer cell wall, it can suck out the cell contents and gather all of the algal plastids at once,” he said.

Based on studies of other sea slugs, some scientists have argued that they steal and store plastids as food to be digested during hard times, like camels that store fat in their humps, Bhattacharya said. This study showed that’s not the case for solar-powered Elysia chlorotica.

“It has this remarkable ability to steal these algal plastids, stop feeding and survive off the photosynthesis from the algae for the next six to eight months,” he said.

The team of Rutgers and other scientists used RNA sequencing (gene expression) to test their solar energy supply hypothesis. The data show that the slug responds actively to the stolen plastids by protecting them from digestion and turning on animal genes to utilize the algal photosynthetic products. Their findings mirror those found in corals that maintain dinoflagellates (also algae) — as intact cells and not stolen plastids — in symbiotic relationships.

Whereas Elysia chlorotica stores plastids, the algal nuclei that are also sucked in don’t survive, and scientists still don’t know how the sea slug maintains the plastids and photosynthesis for months without the nuclei that are normally needed to control their function, Bhattacharya said.