Prehistoric Norfolk pine relative trees discovered

This 2019 video is called Norfolk Island Pine Care.

From Penn State University in the USA:

New Argentine fossils uncover history of celebrated conifer group

June 18, 2020

Newly unearthed, surprisingly well-preserved conifer fossils from Patagonia, Argentina, show that an endangered and celebrated group of tropical West Pacific trees has roots in the ancient supercontinent that once comprised Australia, Antarctica and South America, according to an international team of researchers.

“The Araucaria genus, which includes the well-known Norfolk Island pine, is unique because it’s so abundant in the fossil record and still living today,” said Gabriella Rossetto-Harris, a doctoral student in geosciences at Penn State and lead author of the study. “Though they can grow up to 180 feet tall, the Norfolk Island pine is also a popular houseplant that you might recognize in a dentist’s office or a restaurant.”

Araucaria grew all around the world starting about 170 million years ago in the Jurassic period. Around the time of the dinosaur extinction 66 million years ago, the conifer became restricted to certain parts of the Southern Hemisphere, said co-author Peter Wilf, professor of geosciences and associate in the Earth and Environmental Systems Institute (EESI).

Today, four major groups of Araucaria exist, and the timing of when and where these living lineages evolved is still debated, Rossetto-Harris said. One grows in South America, and the other three are spread across New Caledonia, New Guinea and Australia, including Norfolk Island. Many are now endangered or vulnerable species. The Norfolk pine group, the most diverse with 16 species, is usually thought to have evolved near its modern range in the West Pacific well after the Gondwanan supercontinent split up starting about 50 million years ago, Rossetto-Harris added.

Researchers from Penn State and the Museo Paleontológico Egidio Feruglio, Chubut, Argentina, found the fossils at two sites in Patagonia — Río Pichileufú, which has a geologic age of about 47.7 million years, and Laguna del Hunco, with a geologic age of about 52.2 million years. They analyzed the fossil characteristics and compared them to modern species to determine to which living group the fossils belonged. Then they developed a phylogenetic tree to show the relationships between the fossil and living species. They reported their findings in a recent issue of the American Journal of Botany.

Unlike the monkey puzzle trees of the living South American group of Araucaria, which have large, sharp leaves, the Patagonian conifer fossils have small, needle-like leaves and cone remains that closely resemble the Australasian Norfolk Island pine group, according to the researchers. They also found a fossil of a pollen cone attached to the end of a branch, which is also characteristic of the group.

“The new discovery of a fossil pollen cone still attached to a branch is rare and spectacular,” said Rossetto-Harris, who is also an EESI Environmental Scholar. “It allows us to create a more complete picture of what the ancestors of these trees were like.”

The researchers used 56 new fossils from Río Pichileufú to expand the taxonomic description of Araucaria pichileufensis, a species first described in 1938 using only a handful of specimens.

“Historically, scientists have lumped together the Araucaria fossils found at Río Pichileufú and Laguna del Hunco as the same species,” Rossetto-Harris said. “The study shows, for the first time, that although both species belong to the Norfolk pine group of Araucaria, there is a difference in conifer species between the two sites.”

The researchers named the new species from Laguna del Hunco Araucaria huncoensis, for the site where it was found. The fossils are about 30 million years older than many estimates for when the Australasian lineage evolved, according to Rossetto-Harris.

The findings suggest that 52 million years ago, before South America completely separated from Antarctica, and during the first few million years after separation was underway, relatives of Norfolk Island pines were part of a rainforest that stretched across Australasia and Antarctica and up into Patagonia, said Rossetto-Harris.

The change in the Araucaria species from the older Laguna del Hunco site to the younger Río Pichileufú site may be a response to the climatic cooling and drying that occurred after South America first became isolated.

“We’re seeing the last bits of these forests before the Drake Passage between Patagonia and Antarctica began to really widen and deepen and set forth a lot of big climatic changes that would eventually cause this version of Araucaria to go extinct in South America, but survive in the Australian rainforest and later spread and thrive in New Caledonia,” Rossetto-Harris said.

The study shows how tiny details can provide the definition needed to reveal big, important stories about the history of life, Wilf added.

The National Science Foundation, National Geographic Society, Botanical Society of America, Geological Society of America, and Penn State provided funding for this project.

Prehistoric Canadian and Australian animals, new research

Photo: The Canadian Entomologist. The new fossil lacewing species Epinesydrion falklandensis from British Columbia, Canada, with an almost complete wing

From Simon Fraser University in Canada:

New fossil discovery shows 50 million-year-old Canada-Australia connection

June 15, 2020

The discovery of a tiny insect fossil is unearthing big questions about the global movement of animals and the connection to changes in climate and shifting continents across deep time. The fossil, estimated to be 50 million years old, was found in rocks near the city of Kamloops, British Columbia, but today its relatives live exclusively in Australia.

The finding is the latest in a pattern of discoveries that are leading experts to contemplate a Canada-Australia connection not previously considered. Paleontologists Bruce Archibald of Simon Fraser University and the Royal British Columbia Museum and Vladimir Makarkin of the Russian Academy of Sciences in Vladivostok published their findings in The Canadian Entomologist.

According to Makarkin, the fossil is part of the “split-footed lacewing” family. Little is known about this group over the 66-million-years following the extinction of the dinosaurs. “These fossils are rare,” he says. “This is only the fourth one found from this time-span worldwide, and it’s the most completely preserved. It adds important information to our knowledge of how they became modern.”

The paleontologists identified the fossil by the characteristic network of veins covering its wings. They emphasize that fossils like the new lacewing species help in understanding large-scale patterns of the modern distribution of life across the globe.

Previous fossil insects of this age found in B.C. and neighbouring Washington have shown connections with Pacific-coastal Russia to the west and with Europe to the east — patterns that are not surprising since the northern continents were connected then.

“Fifty million years ago, sea levels were lower, exposing more land between North America and Asia, and the Atlantic Ocean had not widened, leaving Europe and North America still joined across high latitudes,” says Archibald. He explains that the far-north experienced warmer climates then as well, helping a variety of animals and plants to disperse freely between northern continents.

The Australian connection is more puzzling though, as there is no such clear land connection. That continent was closer to Antarctica then and farther from Asia than today, leaving formidable ocean barriers for life to disperse between it and Canada’s west coast.

This lacewing joins other insect fossils from B.C. and Washington whose modern relatives only live in the Australian region. These include bulldog ants, a family of termites, and a kind of parasitoid wasp.

Archibald says that “a pattern is emerging that we don’t quite understand yet, but has interesting implications.”

The researchers suggest that the answer might be connected to climate. The forests of the ancient British Columbian temperate upland where this lacewing lived had very mild winters, in fact, probably without frost days.

The climate of modern Australia shares these mild winters even in temperate regions. “It could be that these insect groups are today restricted to regions of the world where climates in key ways resemble those 50 million years ago in the far western Canadian mountains,” says Archibald.

Archibald and Makarkin emphasise that it’s important to understand the little things in order to appreciate the big picture. “The more we know about these insects, the more we can piece together the history of how climate and the movement of continents have shaped global patterns of the distributions of life that we see in our modern world,” says Makarkin.

“To understand where we are today and where we may be going with the big changes that we are seeing in global climates, we need to understand what’s happened in the deep past.”

Ancient anchovy ancestors were predators

This 2015 video says about itself:

A migration of 10 million anchovies provides an irresistible opportunity for many ocean predators. The swarming, confusing “bait balls” formed by large schools of small and nimble anchovies provide a formidable defense against any one shark hunting alone. However, blacktip sharks have evolved to overcome this challenge.

By Carolyn Wilke, 18 April 2020:

Saber-toothed anchovy relatives hunted in the sea 50 million years ago

Fossils suggest these ancient animals grew up to a meter long and ate other fish

Less pizza topping and more toothy hunter, ancient anchovy kin once had quite the bite.

Fossils show that these fish were armed with a mouthful of fearsome teeth. Each of the two newly analyzed specimens sport spiky teeth along the lower jaw and one giant dagger jutting down from the top jaw. Stranger still, the single sabertooth sits off-center. Such chompers suggest that the now-extinct fish were predators, possibly feeding on other fish, scientists report May 13 in Royal Society Open Science.

Today’s anchovies feast mostly on plankton. “They have super tiny teeth. They look nothing like these things,” says paleontologist Alessio Capobianco of the University of Michigan in Ann Arbor. The ancient fish were also large compared with their modern relatives, which top out at around 37 centimeters. One of the fossil fish may have stretched nearly a meter long, the researchers estimate.

Using CT scans to peer into the fossils, Capobianco and his team discovered shared physical features that tie the ancient fish to their modern kin. Just like today’s anchovies, which open wide to gulp food, these fossil fish had a gaping maw, Capobianco says. “Probably that mouth opening helps to catch fish … because those teeth are so large.”

The fossils, which date from roughly 50 million years ago, are helping fill in a picture of marine life during the Eocene Epoch. At that time, predatory fish like these may have evolved to fill voids left by the massive extinction event that wiped out the dinosaurs along with many marine species about 66 million years ago (SN: 8/2/18).

Fish from groups still around today, such as tuna, barracudas and mackerel, also swam the seas with the anchovies. “There were sort of failed experiments going on at the same time,” Capobianco says, including “these saber-toothed anchovies that didn’t survive to the modern day.”

Colours of cassowaries and extinct birds

This 2019 video is called Giant Cassowaries are Modern-day Dinosaurs | Seven Worlds, One Planet | BBC Earth.

From the Field Museum in the USA:

Microscopic feather features reveal fossil birds’ colors and explain why cassowaries shine

May 13, 2020

Summary: Some birds are iridescent because of the physical make-up of their feathers, but scientists had never found evidence of this structural color in the group of birds containing ostriches and cassowaries — until now. Researchers have discovered both what gives cassowary feathers their glossy black shine and what the feathers of birds that lived 52 million years ago looked like.

Cassowaries are big flightless birds with blue heads and dinosaur-looking feet; they look like emus that time forgot, and they’re objectively terrifying. They’re also, along with their ostrich and kiwi cousins, part of the bird family that split off from chickens, ducks, and songbirds 100 million years ago. In songbirds and their relatives, scientists have found that the physical make-up of feathers produce iridescent colors, but they’d never seen that mechanism in the group that cassowaries are part of — until now. In a double-whammy of a paper in Science Advances, researchers have discovered both what gives cassowary feathers their glossy black shine and what the feathers of birds that lived 52 million years ago looked like.

“A lot of times we overlook these weird flightless birds. When we’re thinking about what early birds looked like, it’s important to study both of these two sister lineages that would have branched from a common ancestor 80 million or so years ago,” says Chad Eliason, a staff scientist at the Field Museum and the paper’s first author.

“Understanding basic attributes — like how colors are generated — is something we often take for granted in living animals. Surely, we think, we must know everything there is to know? But here, we started with simple curiosity. What makes cassowaries so shiny? Chad found an underlying mechanism behind this shine that was undescribed in birds. These kinds of observations are key to understanding how color evolves and also inform how we think about extinct species,” says Julia Clarke, a paleontologist at the Jackson School of Geosciences at the University of Texas at Austin and the paper’s senior author. Eliason began conducting research for this paper while working with Clarke at the University of Texas as part of a larger project funded by the National Science Foundation (NSF EAR 1355292) to study how flightless birds like cassowaries have evolved their characteristic features.

In humans and other mammals, color mostly comes from pigments like melanin that are in our skin and hair. Birds’ colors don’t just come from pigment — some of their coloration, like the rainbow flecks on hummingbirds and the shiny, glossy black on crows, is due to the physical makeup of their feathers. The parts of their cells that produce pigment, called melanosomes, affect the feathers’ color based on how light bounces off those melanosomes. Different shapes or arrays of melanosomes can create different structural colors, and so can the layers of keratin making up the birds’ feathers. They can reflect a rainbow of light, and they can make the difference between dull, matte feathers and feathers with a glossy shine.

Scientists had never found structural colors in the feathers of paleognaths like cassowaries and ostriches — only in the neognath group of birds like songbirds. But paleognaths can make structural colors: the blue skin on cassowaries’ heads is due to structural color, and so is the shiny sheen on eggs laid by their cousins, the tinamous. Eliason and Clarke, who study structural colors in birds and dinosaurs, wanted to see if structural color was also present in paleognath feathers.

A bird’s feather is structured a little like a tree. The long trunk running through the middle is called the rachis, and it has branches called barbs. The barbs are covered with tiny structures called barbules, akin to the leaves on tree branches. In other shiny birds, glossiness is produced by the shape of the barbs and layers of melanosomes in barbules. Eliason and Clarke didn’t find that in cassowary feathers, though. Instead, they discovered that the shiny black color came from the rachis running down the middle of the feathers. Since the fluffy barbules on cassowary feathers are pretty sparse, the rachis gets more exposure to light than in “thick-feathered” birds, giving it a chance to literally shine.

In addition to finding structural color in cassowary feathers, Eliason and Clarke also explored the feathers of a cousin of the cassowary that lived 52 million years ago. The extinct bird Calxavis grandei lived in what’s now Wyoming, and its incredibly well-preserved fossils include imprints of its feathers.

“You can look at a fossil slab and see an outline of where their feathers were, because you kind of see the black stain of melanin that’s left over, even after you 50 million years or so,” explains Eliason. “We peeled off little flakes of the fossil from the dark spots of melanin, and then we used scanning electron microscopes to look for remnants of preserved melanosomes.”

By examining these feather imprints on a microscopic level, the researchers were able to see the shape of the pigment-producing melanosomes in the leaf-like barbules of the feathers. The melanosomes were long, skinny, and green bean-shaped, which in modern birds is associated with iridescence.

Before this study, scientists had never found evidence of structural color in paleognath feathers — now, they’ve got two different examples. The researchers aren’t sure why cassowaries and the fossil birds evolved two different ways to build shiny feathers — why reinvent the wheel? Eliason suspects that flightlessness might have given cassowaries more room to experiment with their feathers. In flighted birds, including the fossil birds in this study, the number one priority for feather structure is being aerodynamic. Since cassowaries don’t need to worry about flying, they had more evolutionary leeway to develop their oddly-shaped, thick-spined feathers. “Needing to be able to fly is a very strong stabilizing force on wing shape,” says Eliason. “Losing that constraint, that need to fly, might result in new feather morphologies that produce gloss in a way that a flying bird might not.”

In addition to the questions this study poses about why these birds’ feathers evolved so differently, Eliason and Clarke note that it gives us a better overall understanding of life on Earth. “It gives us a glimpse into the time when dinosaurs were going extinct and the birds were rising,” says Eliason. “Studying these paleognaths gives us a better understanding of what was happening there, because you can’t just study neognaths; you need to study both sister clades to understand their ancestors.”

First frog fossil from Antarctica discovered

This video says about itself:

Saturday, 25 April 2020

First frog fossil found on Antarctica

In 2015, Thomas Mörs reached for a frog in the sand — but the frog didn’t hop away. That’s because the frog had been fossilized 40 million years ago.

By Maria Temming, April 23, 2020 at 11:00 am:

The first frog fossil from Antarctica has been found

An ancient amphibian sheds light on when the continent iced over

The first fossil of a frog found in Antarctica gives new insight into the continent’s ancient climate.

Paleontologists uncovered fragments of the frog’s hip bone and skull in 40-million-year-old sediment collected from Seymour Island, near the tip of the Antarctic Peninsula.

Scientists have previously found evidence of giant amphibians that walked Antarctica during the Triassic Period, over 200 million years ago, but no traces on the continent of amphibians like those around today (SN: 3/23/15). The shape of the newly discovered bones indicates that this frog belonged to the family of Calyptocephalellidae, or helmeted frogs, found today in South America.

The fossilized frog’s modern relatives live exclusively in the warm, humid central Chilean Andes. This suggests that similar climate conditions existed on Antarctica around 40 million years ago, researchers report April 23 in Scientific Reports.

That offers a clue about how fast Antarctica switched from balmy to bitter cold (SN: 4/1/20). Antarctica quickly froze over after splitting from Australia and South America, which were once all part of the supercontinent Gondwana (SN: 10/10/19). But some geologic evidence suggests that ice sheets began forming on Antarctica before it fully separated from the other southern continents about 34 million years ago.

“The question is now, how cold was it, and what was living on the continent when these ice sheets started to form?” says study coauthor Thomas Mörs, a paleontologist at the Swedish Museum of Natural History in Stockholm. “This frog is one more indication that in [that] time, at least around the Peninsula, it was still a suitable habitat for cold-blooded animals like reptiles and amphibians.”

German fossil Eocene tapirs, horses, new research

This 1 September 2015 video from the USA says about itself:

Chasing History: Wyoming’s Famous Fossil History, Fossil Fish, The Eocene Epoch

In this Adventure go Exploring with Chase as he and Professional Fossil Hunter JJ Surprise dive into the Eocene Epoch of Wyoming’s Fossil Lake, and show you how you can discover your own piece of Wyoming’s Past!

From the Martin-Luther-Universität Halle-Wittenberg in Germany:

Small horses got smaller, big tapirs got bigger 47 million years ago

Researchers open a window onto ancient mammal evolution using fossils from Germany

March 24, 2020

The former coalfield of Geiseltal in Saxony-Anhalt has yielded large numbers of exceptionally preserved fossil animals, giving palaeontologists a unique window into the evolution of mammals 47 million years ago. A team led by the University of Tübingen and the Martin Luther University Halle-Wittenberg (MLU) has shown that the body size of two species of mammals developed in opposite directions. The study was published in “Scientific Reports”.

47 million years ago — the middle Eocene — the Earth was much warmer and the area of Geiseltal was a swampy subtropical forest whose inhabitants included ancestors of the horse, ancient tapirs, large terrestrial crocodiles, as well as giant tortoises, lizards and ground-dwelling birds. So rich are the Geiseltal finds that they give researchers an unprecedented high-resolution picture of evolutionary dynamics at the population level.

A team led by Dr Márton Rabi from the University of Tübingen and the Martin Luther University Halle-Wittenberg (MLU) has shown that the body size of two species of mammals developed in opposite directions. The study, published in Scientific Reports, was carried out with Simon Ring and Professor Hervé Bocherens at the Senckenberg Centre for Human Evolution and Palaeoenvironment and the University of Tübingen in cooperation with Dr Oliver Wings from the MLU.

“We were initially interested in the evolution of the ancient horses, which were about the size of a Labrador dog. These animals are particularly abundant in the Geiseltal fossil record,” Rabi says. Researchers initially believed they had several species of early horse. “However, we found that here, there was only one species, whose body size shrank significantly with time,” Rabi explains. The team wanted to test whether this body size shift was climate-induced, since past global warming caused body-size reduction in ancient mammals.

Carbon and oxygen isotope studies on fossil teeth provided the scientists with information about the local middle Eocene climate. “They indicate a humid tropical climate. However, we didn’t find any evidence for climatic changes in Geiseltal over the period investigated,” says Bocherens. To further test the data, the team sought to discover whether the dwarfing process was unique to the horses. For comparison, they examined the evolution of the tapir ancestor called Lophiodon. “We had reason to question the Geiseltal’s constant-climate data; so we expected that other mammals would show the same body-size trends as the horses,” Simon Ring explains. In a surprising result, the tapirs — also a single species — revealed the opposite trend. They grew larger instead of shrinking. While the ancestors of the horse shrank from an average body weight of 39 kilograms to around 26 kilograms over about a million years, the tapirs increased from 124 kilograms to an average body weight of 223 kilograms.

Differing survival strategies

“All the data indicate that the body size of the horses and tapirs developed differently not because of the climate, but because of different life cycles,” explains Bocherens. Small animals reproduce faster and die younger: Relative to their size, they don’t have to eat as much to maintain their body mass and can devote more resources to having young. Larger animals live longer and have lower reproduction rates. They have to eat more and therefore have fewer resources for reproduction — but, being large, face fewer predators and can range further to get better food. That extends their lives and gives them more time to breed. The Geiseltal tapirs and the horses therefore likely maximized the different advantages of their respective life cycle strategies, which caused divergent body size evolution.

Exceptional fossil deposits

The Geiseltal fossil site is located in the eastern state of Saxony-Anhalt. In the course of open-cast brown coal mining between 1933 and 1993, tens of thousands of fossil specimens of more than one hundred species were discovered there. Many were the ancestors of modern vertebrates. “The Geiseltal is as important a fossil site as the Messel Pit near Darmstadt, which is a UNESCO World Heritage Site,” says Dr. Rabi. “But because the Geiseltal collection was hardly accessible during East German times, it kind of went off the radar.”

‘Oldest bamboo’ fossil was really a conifer

Chusquea oxyphylla, phоto: Phytokeys

From ScienceDaily:

‘Oldest bamboo’ fossil from Eocene Patagonia turns out to be a conifer

February 4, 2020

A fossilised leafy branch from the early Eocene in Patagonia described in 1941 is still often cited as the oldest bamboo fossil and the main fossil evidence for a Gondwanan origin of bamboos. However, a recent examination by Dr. Peter Wilf from Pennsylvania State University revealed the real nature of Chusquea oxyphylla. The recent findings, published in the paper in the open-access journal Phytokeys, show that it is actually a conifer.

The corrected identification is significant because the fossil in question was the only bamboo macrofossil still considered from the ancient southern supercontinent of Gondwana. The oldest microfossil evidence for bamboo in the Northern Hemisphere belongs to the Middle Eocene, while other South American fossils are not older than Pliocene.

Over the last decades, some authors have doubted whether the Patagonian fossil was really a bamboo or even a grass species at all. But despite its general significance, modern-day re-examinations of the original specimen were never published. Most scientists referring to it had a chance to study only a photograph found in the original publication from 1941 by the famous Argentine botanists Joaquín Frenguelli and Lorenzo Parodi.

In his recent study of the holotype specimen at Museo de La Plata, Argentina, Dr. Peter Wilf revealed that the fossil does not resemble members of the Chusquea genus or any other bamboo.

“There is no evidence of bamboo-type nodes, sheaths or ligules. Areas that may resemble any bamboo features consist only of the broken departure points of leaf bases diverging from the twig. The decurrent, extensively clasping leaves are quite unlike the characteristically pseudopetiolate leaves of bamboos, and the heterofacially twisted free-leaf bases do not occur in any bamboo or grass,” wrote Dr. Wilf.

Instead, Wilf linked the holotype to the recently described fossils of the conifer genus Retrophyllum from the same fossil site, the prolific Laguna del Hunco fossil lake-beds in Chubut Province, Argentina. It matches precisely the distichous fossil foliage form of Retrophyllum spiralifolium, which was described based on a large set of data — a suite of 82 specimens collected from both Laguna del Hunco and the early middle Eocene Río Pichileufú site in Río Negro Province.

Retrophyllum is a genus of six living species of rainforest conifers. Its habitat lies in both the Neotropics and the tropical West Pacific.

The gathered evidence firmly confirms that Chusquea oxyphylla has nothing in common with bamboos. Thus, it requires renaming. Preserving the priority of the older name, Wilf combined Chusquea oxyphylla and Retrophyllum spiralifolium into Retrophyllum oxyphyllum.

The exclusion of a living New World bamboo genus from the overall floral list for Eocene Patagonia weakens the New World biogeographic signal of the late-Gondwanan vegetation of South America, which already showed much stronger links to living floras of the tropical West Pacific.

The strongest New World signal remaining in Eocene Patagonia based on well-described macrofossils comes from fossil fruits of Physalis (a genus of flowering plants including tomatillos and ground cherries), which is an entirely American genus, concludes Dr. Wilf.

Prehistoric whales, new discovery

This 2014 video is called Evolution of Whales Animation.

From PLOS:

A new early whale, Aegicetus gehennae, and the evolution of modern whale locomotion

New whale represents an intermediate stage between foot-powered and tail-powered swimming

December 11, 2019

A newly discovered fossil whale represents a new species and an important step in the evolution of whale locomotion, according to a study published December 11, 2019 in the open-access journal PLOS ONE by Philip Gingerich of the University of Michigan and colleagues.

The fossil record of whale evolution tracks the transition from land-dwelling ancestors to ocean-dwelling cetaceans. Protocetids are a group of early whales known from the Eocene Epoch of Africa, Asia, and the Americas. While modern whales are fully aquatic and use their tails to propel themselves through the water, most protocetids are thought to have been semi-aquatic and swam mainly with their limbs. In this study, Gingerich and colleagues describe a new genus and species of protocetid, Aegicetus gehennae.

The new whale was discovered in 2007 in the Wadi Al Hitan World Heritage Site in the Western Desert of Egypt. It is the youngest-known protocetid, dating to around 35 million years ago, and is known from one exceptionally complete skeleton and a partial second specimen, making it among the best-preserved ancient whales. Compared with earlier whales, it has a more elongated body and tail, smaller back legs, and lacks a firm connection between the hind legs and the spinal column. These adaptations indicate an animal that was more fully aquatic and less of a foot-powered swimmer than its ancestors.

The body shape of Aegicetus is similar to that of other ancient whales of its time, such as the famous Basilosaurus. These animals appear to be well-adapted for swimming through undulation of the mid-body and the tail, somewhat as crocodiles swim today. The authors suggest that an undulatory swimming style might represent a transitional stage between the foot-powered swimming of early whales and the tail-powered swimming of modern whales.

The authors add: “Early protocetid whales living 47 to 41 million years ago were foot-powered swimmers, and later basilosaurid and modern whales — starting about 37 million years ago — were tail-powered swimmers. The late protocetid Aegicetus was intermediate in time and form, and transitional functionally in having the larger and more powerful vertebral column of a tail-powered swimmer.”

See also here.

Prehistoric insect evolution in the Eocene

This 17 July 2018 video says about itself:

The Mystery of the Eocene’s Lethal Lake

In 1800s, miners began working in exposed deposits of mud near the town of Messel, Germany. They were extracting oil from the rock and along with the oil, they found beautifully preserved fossils of animals from the Eocene. What happened to these Eocene animals? And why were their remains so exquisitely preserved?

Two additional notes!

-At 00:56, we incorrectly labelled a Darwinius fossil as Thaumaturus. Thaumaturus was a fish and the fossil we show is definitely not a fish.

-Also, an additional image credit is required: Dmitry Bogdanov illustrated the fish we used to show scavengers.

From the Ludwig-Maximilians-Universität München in Germany:

Insect evolution during the Eocene epoch

October 25, 2019

Scientists at Ludwig-Maximilians-Universitaet (LMU) in Munich have shown that the incidence of midge and fly larvae in amber is far higher than previously thought. The new finds shed light on insect evolution and the ecology in the Baltic amber forest during the Eocene epoch.

In the Eocene epoch — between 56 and 33.9 million years ago — much of Northern Europe was covered by a huge forest, now referred to as the Baltic amber forest. The forest was probably dominated by pines and oaks, but also comprised representatives of many other deciduous species and conifers, including tropical taxa. The resins produced by the forest account for all of Europe’s amber, including the samples in which the LMU zoologists Viktor Baranov, Mario Schädel and Joachim T. Haug have now discovered many examples of entrapped midge and fly larvae. In a paper published in the online journal PeerJ, they point out that these finds refute the widespread notion that amber is devoid of such fossils. Their analysis also provides new evidence in relation to the ecology of the amber forests of Eocene age, which supports a new interpretation of this habitat as a warm to temperate seasonal humid forest ecosystem.

Flies and midges (Diptera) make up one of the most diverse groups of insects found in Germany. Their larval forms are an important element of many ecosystems and play a significant role in, for example, the decomposition and recycling of biomass. In spite of their ecological prominence, little is known about the evolution of dipteran larvae, and the fossilized specimens that have so far come to light — in particular those characteristic of terrestrial ecosystems — have so far been little studied. The authors of the new study have now identified more than 100 larvae in amber inclusions assembled by collectors in Northern Germany. The samples described come from either the Baltic or the Bitterfeld section of the amber forest. Most of the dipterans identified, belong to the group known as Bibionomorpha, whose evolutionary history extends over a period of more than 200 million years. With a total of 35 specimens, the group most frequently represented is the genus Mycetobia, which belongs to the Family Anisopodidae (whose members are commonly known as window gnats). Thanks to the abundance of this material, the researchers were able to reconstruct the relative growth rate of these larvae based on the length and width of the head capsule. The results confirmed that these gnats went through four larval stages, just like the present-day representatives of the same group. In addition, their overall morphology is very similar to that of extant window gnats. “Since the morphologies of the other fossil bibionomorphan larvae are also very reminiscent of their recent relatives, we can safely assume that they occupied habitats similar to those of our contemporary forms,” says Baranov, first author of the new paper. The presence of large numbers of Mycetobia larvae among the specimens examined therefore implies that Europe’s amber forests were characterized by moist conditions and an abundance of decaying organic matter. Moreover, the researchers also discovered the first fossilized larva that could be assigned to the [genus] Pachyneura (Diptera, Pachyneuridae) … Recent [species] are associated with dead wood in undisturbed woodland.

“Within the scientific community, a new interpretation of Europe’s amber forests is currently emerging. This is based on paleobotanical and isotope evidence which suggests that these woods constituted a warm-to-temperate seasonal ecosystem. Our findings provide further support for this picture,” Baranov explains. He and his colleagues argue that it is quite conceivable that, under the climatic conditions prevailing in Europe during the Eocene, a subtropical, seasonal forest would have supplied abundant amounts of decaying organic matter in the form of leaf litter and dead plants and animals, as well as bacterial biofilms and fungi. In any case, the dipteran larvae provide an independent source of information that can be used to reconstruct the nature of the paleohabitats. “Perhaps our most surprising find is a larva which we identified as a representative of a previously unknown group,” says Baranov. While this larva belongs among the march flies (Diptera, Bibionidae), it exhibits a very unusual combination of morphological characters which finds no parallel among modern representatives of this group.” In Baranov’s opinion, the specimen may document an experimental phase of their evolution, during which different lineages independently “discovered” similar sets of morphological traits.

Antarctica, from greenery, land mammals, to ice

This 3 October 2019 video says about itself:

When Antarctica Was Green

Before the start of the Eocene Epoch about 56 million years ago–Antarctica was still joined to both Australia and South America. And it turns out that a lot of what we recognize about the southern hemisphere can be traced back to that time when Antarctica was green.

Thanks to Ceri Thomas for the Notiolofos and Antarctodon illustrations! Check out more of Ceri’s paleoart here.

And thanks to Julio Lacerda and Studio 252mya for the Antarctodolops illustrations. You can find more of their work here.