Dinosaurs extinct, buckthorn flowers survived


Two fossilized flowers next to each were discovered in shales of the Salamanca Formation in Chubut Province, Patagonia, Argentina. Credit: Nathan Jud, Cornell University

From Cornell University in the USA:

Oldest buckthorn fossilized flowers found in Argentina

May 11, 2017

Summary: Around 66 million years ago, at the end of the Cretaceous period, a giant asteroid crashed into the present-day Gulf of Mexico, leading to the extinction of the non-avian dinosaurs. How plants were affected is less understood, but fossil records show that ferns were the first plants to recover many thousands of years afterward. Now, a team reports the discovery of the first fossilized flowers from South America, and perhaps the entire Southern Hemisphere, following the extinction event.

Around 66 million years ago, at the end of the Cretaceous period, a giant asteroid crashed into the present-day Gulf of Mexico, leading to the extinction of the non-avian dinosaurs. How plants were affected is less understood, but fossil records show that ferns were the first plants to recover many thousands of years afterward.

Now, a team including Cornell researchers reports the discovery of the first fossilized flowers from South America, and perhaps the entire Southern Hemisphere, following the extinction event. The fossils date back to the early Paleocene epoch, less than one million years after the asteroid struck. They were discovered in shales of the Salamanca Formation in Chubut Province, Patagonia, Argentina.

The researchers identified the fossilized flowers as belonging to the buckthorn family (Rhamnaceae). Today, the family is found worldwide.

The study was published May 10 in the online journal PLOS One. “The fossilized flowers provide a new window into the earliest Paleocene communities in South America, and they are giving us the opportunity to compare the response to the extinction event on different continents,” said Nathan Jud, the paper’s first author and a postdoctoral researcher in Maria Gandolfo’s lab, a senior research associate at the L.H. Bailey Hortorium and a co-author of the paper.

The finding also helps resolve an ongoing debate in the field of paleobotany on the origin of the Rhamnaceae plant family. Scientists have argued about whether early buckthorns originated in an ancient supercontinent called Gondwana, which later split and includes most of the Southern Hemisphere landmasses today; or whether the family originated in another supercontinent called Laurasia that accounts for most of today’s Northern Hemisphere landmasses.

“This, and a handful of other recently-discovered fossils from the Southern Hemisphere, supports a Gondwanan origin for Rhamnaceae in spite of the relative scarcity of fossils in the Southern Hemisphere relative to the Northern Hemisphere,” Jud said.

Fossils found in Colombia and Southern Mexico offer evidence that plants from the Rhamnaceae family first appeared in the Late Cretaceous epoch shortly before the extinction event, Jud said.

Though there was likely some extinction when the asteroid struck, especially near the crater where everything was destroyed by impact-generated wildfires, he added.

One scenario is that Rhamnaceae first appeared in the tropics of Gondwana, but survived the extinction in Patagonia, and then spread from there after the extinction event as plants re-colonized the most affected areas, Jud said.

The Salamanca Formation is among the most precisely-dated sites from that era in the world. The age of the fossils was corroborated by radiometric dating (using radioactive isotopes), the global paleomagnetic sequence (signatures of reversals of Earth’s magnetic field found in the samples), and fossil correlations (age of other fossils).

“These are the only flowers of Danian age [an age that accounts for about 5 million years following the extinction event] for which we have good age control,” said Jud. Researchers have discovered other fossilized flowers in India and China from around the Danian age, but their dates are not as precise, he said.

To determine that the fossilized flowers from Argentina belonged to the Rhamnaceae family, the authors noticed that the organization of the petals and stamens in the fossil is found in Rhamnaceae and a few other families. They found examples of 10 of the 11 living Rhamnaceae tribes in the L.H. Bailey Hortorium Herbarium at Cornell University, which then were compared with morphological features in the fossil flowers to identify them.

Mammals and extinction of dinosaurs


This video says about itself:

31 December 2015

The world after the extinction of the non-avian dinosaurs, when giant birds hunted mammals before they ruled the earth.

From Science News:

With dinosaurs out of the way, mammals had a chance to thrive

After the extinction event, a new crowd of animals had room to explore a reshaped world

By Meghan Rosen

2:30pm, January 25, 2017

For dinosaurs, the end of the world began in fire.

The space rock that stamped a Vermont-sized crater into the Earth 66 million years ago packed a powerful punch. Any animal living within about a thousand miles of the impact zone was probably vaporized, says paleontologist Stephen Brusatte of the University of Edinburgh in Scotland.

“Everything would have been toast.”

But outside of the impact zone, amid the smoking ruins of the battered planet, some survivors emerged.

Life there was no picnic. Wave after wave of life-threatening disasters pummeled the animals that remained, says paleontologist Nicholas Longrich of the University of Bath in England. Earthquakes. Wildfires. Volcanoes. Acid rain. Dust and gunk in the air, blotting out the sun. “It’s this series of biblical plagues,” Longrich says.

With little light, much plant life perished, and entire food webs collapsed, life would have been like an ancient Hunger Games, with all living creatures as contestants. The odds were not in their favor. From sea to land to lake to sky, animals suffered incredible losses.

“You’re basically losing all the big herbivores, all the big carnivores, apex predators in the oceans, entire guilds — wiped out overnight,” Longrich says. On land, he adds, anything bigger than a beaver went extinct. Just a few places in North America offer a fossil record of the early years after the extinction, he says, but “there’s no evidence for anything over 10 kilos surviving.”

Tyrannosaurus rex, Triceratops, Ankylosaurus and all other nonavian dinosaurs gone.

A lucky few animals managed to cope with the dramatic changes reshaping their environment, Brusatte says. But why exactly some animal groups survived and others bit the dust is still one of paleontology’s biggest mysteries.

New fossil research is now helping scientists peer back through time, offering glimmers of what might have been: How some animals made it through one of the worst extinction events the planet has ever seen — and how mammals, in particular, came to dominate.

Sussing out animals’ survival strategies could offer hints about how animals today might handle a changing climate, Brusatte says. It might even expose the evolutionary drivers that shaped modern life. After the extinction, evolution went wild, he says. The survivors “had a new world to play in — a new world to conquer.”

Cretaceous catastrophe

Near the very end of the Late Cretaceous Epoch, right before the world blew up, one of the largest mammals in North America may have been noshing on bones.

Didelphodon vorax, a honey badger–looking creature with oddly bulbous teeth, was petite by today’s standards — weighing just about five kilograms. But it was no lightweight. “Pound for pound, it had the greatest bite force of any mammal we’ve ever measured,” says paleontologist Gregory Wilson of the University of Washington in Seattle.

Wilson and colleagues estimated Didelphodon’s bite force from the shape of its fossilized skull. The mammal could snap its jaws together with about 50 pounds of force — enough to crush bones and crack shells, the team reported December 8 in Nature Communications.

This fearsome skill wasn’t enough to save it: After the asteroid hit and global disasters descended, Didelphodon went extinct — just like duck-billed dinosaurs and Pteranodon.

The colossal wipeout of Didelphodon and so many others is plain to see in the fossil record. In Montana’s badlands, where Wilson and colleagues hunt for ancient teeth and bones, tributaries of the Missouri River carve steep bluffs into the earth, exposing slabs of sandstone and siltstone rock. Montana is part of the Western Interior, an ancient seaway that once cut a wide aisle through North America from the Gulf of Mexico to the Arctic.

Much of what scientists know about the dino-killing event, called the Cretaceous–Paleogene, or K–Pg, extinction, traces back to this sweeping tract of land. The area has rocks with fossils from before and after the extinction event. “We haven’t found many places in the world like it,” Wilson says. Spain, France and Romania hold a few dinosaur and mammalian fossils from this time period (and a handful of underexplored spots in India and South America may offer more). But so far, the Western Interior is home to the best land-based record scientists have.

In Montana, the rocks capture a snapshot of time from about 2 million years before the extinction to roughly 1.5 million years after. A thin layer of reddish-brown clay marks the before and after of the asteroid’s impact. “It’s a line in the sand, almost literally,” Brusatte says. Within the clay, here and elsewhere in the world, scientists find elevated levels of iridium, a silvery-white metal carried to Earth via asteroid. Though not visible by eye (scientists need chemical tests to spot it), the metallic dust marks a memory of the impact known as Chicxulub.

All around the globe, Brusatte says, scientists see “a knife-edge separation in the rock” before and after Chicxulub hit. “For over 150 million years you have tons and tons of dinosaur bones, and then literally — Bam! There’s nothing.”

Dinosaurs were among the animal groups hit hardest by the extinction. Others suffered fewer casualties. In what is now northeastern Montana, about half of fish species survived, Wilson reported at an Origins Project workshop at Arizona State University in 2015. Turtles and salamanders seemed to fare the best, losing only roughly a quarter of their species, Wilson and colleagues reported in a series of studies in 2014.

“Most people think that mammals did awesome,” Wilson says. But at least 75 percent of mammals were snuffed out, according to his analysis, which compared fossils present before and after the extinction. Longrich and colleagues put the number even higher: Of 59 mammalian species living in North America during the Late Cretaceous Epoch, about 93 percent died out after the asteroid hit. Those calculations appeared in the Journal of Evolutionary Biology in August 2016.

Still, some species found a way to endure.

Survival strategies

A small body. An aquatic lifestyle. Night vision. An unfussy palate. Any one of these features could have helped survivors withstand the relentless undoing of their ecosystems.

It makes sense. Small animals would have required less food than large ones and may have had an easier time finding shelter. Animals that lived in water could have been buffered from dramatic temperature swings.

Nocturnal animals would have been able to hunt for food when debris-filled skies wrapped the world in gloom. The right diet, in fact, could have been one of the biggest tickets to survival. Among insects, for instance, the difference between survival and demise depended on dietary diversity.

Some insects are adventurous eaters: They feed on lots of different kinds of plants. Other insects are pickier. Leaf miners, for example, typically dine on just one plant species, or a few closely related ones, which made it hard to survive the cataclysm.

These insects burrow through leaves, leaving behind a distinctive trail. Cataloging the trails and other damage patterns on fossil leaves can give researchers a rough idea of the kinds of insects that went extinct — or survived, says Penn State paleontologist Michael Donovan. It’s like a calling card stamped into stone.

Donovan examined 3,646 fossil leaves found in Patagonia, Argentina, from slices of time bracketing the Chicxulub impact. The leaf-mining patterns seen before the impact vanished after the asteroid hit, he and colleagues reported in Nature Ecology & Evolution in 2016.

That suggests a major extinction of leaf-mining insects, a find echoed in previous results from North Dakota. (Though not all perished. Donovan saw new leaf-mining patterns after the extinction). Other types of leaf damage did persist through the extinction event — damage made by insects that eat many plant species. Unlike leaf miners, these insects took what they could get in the dark days after the impact. “That’s probably a good way to survive,” Donovan says.

This type of strategy may have helped some species adapt to their new habitat, Longrich says, which after the K–Pg extinction “happened to be this post-apocalyptic wasteland world.” It’s like Mad Max of the movies, he says. “A guy who’s super versatile — good at many different things,” Longrich says, “that’s who’s likely to live through an apocalypse.”

Some animals may have already been plugged into the right food chain. When dinosaurs began dying and leaves fell from trees, the bodies and detritus would have littered the ground and washed into rivers and lakes. That would have been a bonanza for the garbage disposal crew. Decaying matter could feed microbes and fish and insects, which could then feed larger animals, like crocodiles and mammals.

Birdlike dinosaurs with beaks could have cracked into another Cretaceous leftover: seeds. The calorie-rich food could have lasted for decades, says paleontologist Derek Larson of the Philip J. Currie Dinosaur Museum in Alberta and the University of Toronto. Other birdlike dinosaurs, with sharp teeth but no beaks, would have had trouble eating seeds. That might explain why they succumbed, while their close relatives — ancestors of modern birds — survived, he and colleagues suggested last year in Current Biology (SN: 5/14/16, p. 11).

Making it as a mammal

Mammals seemed to capitalize on the detritus-based food chain too, Wilson says. He and University of Washington student Stephanie Smith studied fossils found in northeastern Montana from a 1.2-million-year window after the impact. “Fossil mammals are mostly just teeth,” Smith said at the 2016 Society of Vertebrate Paleontology meeting in Salt Lake City. “Luckily, teeth contain a lot of information.”

Smith compared the intricate details of fossil teeth with those from living mammals to learn about the ancient animals’ diets. In Montana, at least, mammals that lived during the first 200,000 years after the extinction event tended to have teeth that were good for crunching insects — “sharp and pointy,” Wilson says. These animals would have had a reliable source of supper. But plant eaters, which have teeth with big basins for grinding and crushing, would have seen their food supplies wither.

For some mammals, a sharp sense of smell could also have offered a competitive edge. Onychodectes tisonensis, a bull dog–sized mammal that lived about 350,000 years after the extinction, had one of the largest olfactory bulbs of any mammal (relative to the cerebrum) — bigger than those found in even expert sniffers like modern dogs and pigs. The smell organs look like two almonds sticking out from the front of the brain, says James Napoli of Brown University in Providence, R.I., who reported the results at the paleontology meeting last year. He and colleagues built a digital model based on a CT scan of an Onychodectes skull unearthed in New Mexico in 1892.

Having big olfactory bulbs means the animal would have been good at nosing out meals, a valuable skill when food is scarce, Napoli says.

Onychodectes belongs to a weird group of mammals called taeniodonts, says study coauthor Thomas Williamson of the New Mexico Museum of Natural History and Science in Albuquerque. “They have bizarre-looking skulls, enlarged forearms, big claws,” he says. The animals may have survived by digging up and eating tough roots and tubers. “We call them the pigs of the Paleocene.”

Paleontologists don’t know for sure if this group of animals lived through the asteroid crash, or if they arose afterward. There’s just one reported taeniodont fossil from the Late Cretaceous — a partial skull from Alberta, Canada.

If taeniodonts did make it through the impact and its aftermath, an aptitude for rooting out hidden food caches would have been useful. If, instead, the animal group emerged later, Onychodectes could have been one of the early examples of mammalian experimentation.

For more than 150 million years, mammals had been “kept under the thumb of the dinosaurs,” Wilson says. After the extinction, with dinosaurs out of the picture, the “Age of Mammals” could begin.

Boomtime for mammals

In the years after the impact, the world was like a school playground that had banished the big kids.

The animals that survived the early hard years gave rise to a slew of new species able to fill the niches left behind by dinosaurs — and all the other creatures that didn’t make it. Before the impact, humans’ ancestors mostly scurried along the ground. But afterward, with fewer predators and competitors, they were free to try out new lifestyles, like living in trees and gliding.

Placental mammals, a group that includes humans, elephants and most mammals living today, experienced a big evolutionary boom, says Thomas Halliday, a paleobiologist at University College London. “Diversification exploded.”

Without dinosaurs breathing down their necks and with fewer competitors, placental mammals had “freedom to evolve in a variety of new directions,” Halliday says. It’s like they were “exploring almost every aspect of the ways of being a mammal.”

When exactly these mammals arose and how much dinosaurs were holding them back remains controversial: Molecular evidence places their origin tens of millions of years before the dinosaurs died. Fossil evidence puts it closer to the K–Pg extinction.

In a series of papers published in 2015 and 2016, Halliday and colleagues analyzed mammalian fossils to sketch out a clearer picture of placental mammals’ history. First, the team built a family tree focused on placental mammals that lived in the Paleocene, the 10-million-year epoch immediately following the extinction. That’s no easy feat, Halliday says, because these animals tend to lack the kind of standout features that would clearly label them as members of one group or another.

So he and colleagues created an exhaustive catalog of 680 body features (such as skull length, tooth number and molar shape) in 177 genera of extinct and living placental mammals and their close relatives. Presumably, animals that shared features were more closely related than those that didn’t. With so many species, the web of potential relationships was astronomical, Halliday says. “There were more possible arrangements … than there are hydrogen atoms in the universe.” The team plugged the data into a computer, which chugged through all the possibilities and came up with the most likely family tree.

Then, the researchers used the tree to calculate rates of evolution. Placental mammals, they found, probably did originate in the Late Cretaceous, but they evolved three times faster after the extinction event than in the 80 million years before it. “We’re talking about new anatomical innovations,” Halliday says: molars good for grinding leaves, limbs adapted for climbing or swimming.

One of these early innovators was Periptychus carinidens, a muscular animal that walked like a bear and had five toes with “weird little hooves,” says University of Edinburgh paleontologist Sarah Shelley. “It’s not like anything alive today.”

Shelley, Williamson and Brusatte described Periptychus fossils found in New Mexico’s San Juan Basin at the 2016 paleontology meeting. “They have really strange cheek teeth,” Williamson says. The teeth are enlarged and conical with big ridges that run from the base to the tip. He thinks Periptychus used its weird chompers to eat hard objects — seeds, perhaps, or unripe fruit.

Periptychus was among the first plant-eating placental mammals to emerge after the extinction — and for a few million years it flourished. Fossils of the animal have been found from West Texas to eastern Montana, Williamson says. “It must have been a highly successful mammal.” But Periptychus couldn’t cope with changes that came later — it died out about 60 million years ago. The animals “were early experiments,” he says, “but they were ultimately dead ends.”

That’s how it goes with evolution, Halliday says. After the dinosaurs died and mammals tested out different modes of life, some found success and others fizzled. “The most successful strategies are honed and the less successful ones are pared away,” he says.

What’s left is what we have today: more than 5,400 different mammal species spread across the world. But descending from an evolutionary winner doesn’t guarantee a safe future. As species carve out an ever more ideal niche, they become more and more vulnerable to extinction, Halliday says. Animals built for a narrow mode of living tend to have a hard time handling disruptions to their environment. And as the climate changes, some species have already begun to suffer. “In the metaphorical sense, we are in the middle of the asteroid strike right now,” he says.

Already, a changing climate has erased pockets of plants and animals across the globe, John Wiens of the University of Arizona in Tucson reported in December 2016 in PLOS Biology. Further warming in coming decades could ramp up extinctions, he warns.

That’s why studying life and death 66 million years ago is still relevant today, Brusatte says. “It’s not just storytelling about the ancient past,” he says. “It can help us understand our modern world,” and maybe even influence conservation strategies to mitigate some of the changes that are happening now.

‘Meteorite killed not only dinosaurs, also most mammals’


This video says about itself:

The Day the Mesozoic Died: The Asteroid That Killed the DinosaursHHMI BioInteractive Video

26 August 2014

Ever wonder why the dinosaurs disappeared? HHMI BioInteractive investigates the cause of the mass extinction at the end of the Cretaceous period—and the clues come from paleontology, chemistry, physics, and biology.

This three-act film tells the story of the extraordinary detective work that solved one of the greatest scientific mysteries of all time. Explore the fossil evidence of these prehistoric animals, and other organisms that went extinct, through this lively educational video.

From daily The Independent in Britain today:

Prehistoric asteroid wiped out nearly all mammals as well as dinosaurs, research suggests

‘More data shows the extinction was more severe than previously believed’

Jack Hardy

Nearly every species of mammal was eradicated by the prehistoric asteroid which wiped out the dinosaurs, research suggests.

Around 93% of mammal species were made extinct by the strike, which took place in the Cretaceous period, more than 66 million years ago.

Examination of fossil records by scientists from the University of Bath determined that the asteroid’s impact had been much more severe than previously thought.

Past estimates have been much lower because some of the rarer species that were killed left a smaller fossil record, researchers said.

The University of Bath’s Dr Nick Longrich said: “The species that are most vulnerable to extinction are the rare ones, and because they are rare, their fossils are less likely to be found.

“The species that tend to survive are more common, so we tend to find them.

“The fossil record is biased in favour of the species that survived. As bad as things looked before, including more data shows the extinction was more severe than previously believed.”

It was also found the asteroid’s catastrophic effect for life on Earth was mitigated by species recovering rapidly.

Within 300,000 years, the number of species on the planet was double the amount that had existed before the mass extinction.

Due to the lack of sustenance resulting from the widespread destruction of vegetation and animals, it is thought that the largest living animal during the period would have been about the size of a cat.

Dr Longrich added: “Because mammals did so well after the extinction, we have tended to assume that it didn’t hit them as hard.

“However, our analysis shows that the mammals were hit harder than most groups of animals, such as lizards, turtles, crocodilians, but they proved to be far more adaptable in the aftermath.

“It wasn’t low extinction rates, but the ability to recover and adapt in the aftermath that led the mammals to take over.”

Researchers analysed all known mammal species in North America from the end of the Cretaceous period to draw their conclusions.

The findings were published in the Journal of Evolutionary Biology.

Prehistoric turtles and climate change


This March 2014 video is called Global Warming 56 Million Years Ago: What it Means for Us .

From the University of Florida in the USA:

Tropical turtle discovery in Wyoming provides climate-change clues

Published: February 23 2015

Tropical turtle fossils discovered in Wyoming by University of Florida scientists reveal that when the earth got warmer, prehistoric turtles headed north. But if today’s turtles try the same technique to cope with warming habitats, they might run into trouble.

While the fossil turtle and its kin could move northward with higher temperatures, human pressures and habitat loss could prevent a modern-day migration, leading to the extinction of some modern species.

The newly discovered genus and species, Gomphochelys (pronounced gom-fo-keel-eez) nanus, provides a clue to how animals might respond to future climate change, said Jason Bourque, a paleontologist at the Florida Museum of Natural History at UF and the lead author of the study, which appears online this week in the Journal of Vertebrate Paleontology</em>.

The wayfaring turtle was among the species that researchers believe migrated 500-600 miles north 56 million years ago, during a temperature peak known as the PaleoceneEocene Thermal Maximum. Lasting about 200,000 years, the temperature peak resulted in significant movement and diversification of plants and animals.

“We knew that some plants and lizards migrated north when the climate warmed, but this is the first evidence that turtles did the same,” Bourque said. “If global warming continues on its current track, some turtles could once again migrate northward, while others would need to adapt to warmer temperatures or go extinct.”

The new turtle is an ancestor of the endangered Central American river turtle and other warm-adapted turtles in Belize, Guatemala and southern Mexico. These modern turtles, however, could face significant roadblocks on a journey north, since much of the natural habitat of these species is in jeopardy, said co-author Jonathan Bloch, a Florida Museum curator of vertebrate paleontology.

“If you look at the waterways that turtles would have to use to get from one place to another, it might not be as easy as it once was,” Bloch said. “Even if the natural response of turtles is to disperse northward, they have fewer places to go and fewer routes available.”

To put the new turtle in evolutionary context, the researchers examined hundreds of specimens from museum collections around the country, including turtles collected during the 1800s housed at the Smithsonian Institution. Co-author Patricia Holroyd, a vertebrate paleontologist at the University of California, Berkeley, said the fossil history of the modern relatives of the new species shows they could be much more wide-ranging, if it were not for their restricted habitats.

The Central American river turtle is one of the most endangered turtles in the world, threatened by habitat loss and its exploitation as a human food source, Holroyd said.

“This is an example of a turtle that could expand its range and probably would with additional warming, but — and that’s a big but — that’s only going to happen if there are still habitats for it,” she said.

Purgatorius, world’s oldest primate?


This video says about itself:

PurgatoriusExtinction of the Dinosaurs

29 November 2014

Purgatorius and the extinction of the dinosaurs.

Scenes from Animal Planet‘s Animal Armageddon.

From Proceedings of the National Academy of Sciences of the United States of America:

Oldest known euarchontan tarsals and affinities of Paleocene Purgatorius to Primates

Significance

Purgatorius has been considered a plausible ancestor for primates since it was discovered, but this fossil mammal has been known only from teeth and jaw fragments. We attribute to Purgatorius the first (to our knowledge) nondental remains (ankle bones) which were discovered in the same ∼65-million-year-old deposits as dentitions of this putative primate. This attribution is based mainly on size and unique anatomical specializations known among living euarchontan mammals (primates, treeshrews, colugos) and fossil plesiadapiforms.

Results of phylogenetic analyses that incorporate new data from these fossils support Purgatorius as the geologically oldest known primate. These recently discovered tarsals have specialized features for mobility and provide the oldest fossil evidence that suggests arboreality played a key role in earliest primate evolution.

Abstract

Earliest Paleocene Purgatorius often is regarded as the geologically oldest primate, but it has been known only from fossilized dentitions since it was first described half a century ago. The dentition of Purgatorius is more primitive than those of all known living and fossil primates, leading some researchers to suggest that it lies near the ancestry of all other primates; however, others have questioned its affinities to primates or even to placental mammals.

Here we report the first (to our knowledge) nondental remains (tarsal bones) attributed to Purgatorius from the same earliest Paleocene deposits that have yielded numerous fossil dentitions of this poorly known mammal. Three independent phylogenetic analyses that incorporate new data from these fossils support primate affinities of Purgatorius among euarchontan mammals (primates, treeshrews, and colugos).

Astragali and calcanei attributed to Purgatorius indicate a mobile ankle typical of arboreal euarchontan mammals generally and of Paleocene and Eocene plesiadapiforms specifically and provide the earliest fossil evidence of arboreality in primates and other euarchontan mammals. Postcranial specializations for arboreality in the earliest primates likely played a key role in the evolutionary success of this mammalian radiation in the Paleocene.

Flowering plants after dinosaur extinction


This video is called Angiosperm (flowering plant) Life Cycle.

From Smithsonian.com in the USA:

Flowering Plants Appeared in Forest Canopies Just a Few Million Years After Dinosaurs Went Extinct

A new study gives scientists some more insight into the weird history of flowering plants

By Mary Beth Griggs

Taking a minute to smell the flowers isn’t that hard nowadays, but angiosperms (a.k.a. flowering plants) weren’t always as ubiquitous as they are now. They appeared rather suddenly in the fossil record, definitively showing up around 132 million years ago. Their sudden appearance has puzzled scientists from Darwin on to the present day, and while today we understand a bit more about how they diversified, scientists are still learning new things about their history.

In a new study published in Geology, scientists think that they’ve figured out another piece of the angiosperm puzzle. Researchers looked at the patterns of leaf veins of flowering plants in tropical forests in Panama and a temperate forest in Maryland. They looked at the leaves of 132 species, reaching the top of the forest canopy with a 131-foot tall crane, and also taking a look at the leaves that had fallen to the forest floor. Leaves that originated at the very top of the trees tended to have a denser collection of veins than the ones further down the tree trunk.

The scientists then compared the patterns found on the leaves in the forests to leaves found in the fossil record, and discovered that flowering plants had reached the heights of the forest canopy around 58 million years ago, during the Paleocene, just a few million years after the dinosaurs went extinct.

Dinosaurs got extinct, how about dinosaur age plants?


This video says about itself:

The Day The Mesozoic Died HD

30 May 2013

The disappearance of the dinosaurs at the end of the Cretaceous period posed one of the greatest, long-standing scientific mysteries. This three-act film tells the story of the extraordinary detective work that solved it. Shot on location in Italy, Spain, Texas, Colorado, and North Dakota, the film traces the uncovering of key clues that led to the stunning discovery that an asteroid struck the Earth 66 million years ago, triggering a mass extinction of animals, plants, and even microorganisms. Each act illustrates the nature and power of the scientific method. Representing a rare instance in which many different disciplines—geology, physics, biology, chemistry, paleontology—contributed to a revolutionary theory, the film is intended for students in all science classes.

From Laelaps blog today:

Planting the Cenozoic Garden

by Brian Switek

Sixty six million years ago, a global catastrophe extinguished the non-avian dinosaurs. This is common knowledge. It’s also too narrow a view. Various forms of life disappeared in the same geologic instant – from coil-shelled ammonites to some forms of mammal – and others, for reasons as yet unknown, survived.

Plants are among the neglected of the victims and survivors. A magnolia tree does not hold the same cultural cachet as Tyrannosaurus. The post-impact “fern spike” is often cited as a symbol of wide-ranging devastation, but, outside technical journals, that’s about the extent of our attention span for paleoflora. That’s a shame. If we’re going to understand how life on Earth was so deeply wounded 66 million years ago, and how it bounced back, we should be looking more closely at the prehistoric garden.

Hot on the heels of a review summarizing the global dinosaurian picture at the end of the Cretaceous, Lund University paleobotanists Vivi Vajda and Antoine Bercovici have now assembled a view of how plants were affected by the Earth’s fifth mass extinction. Prehistoric pollen and spores tell the story.

The advantage of looking at fossil pollen, Vajda and Bercovici write, is that there’s plenty of it. That’s not only because plants produce large amounts of the reproductive material, but because pollen is also incredibly durable. If you want to see who’s living where, and how environments change through time, these microscopic plant fossils are good way to do it.

In some ways, the story of the Cretaceous plants echoes what paleontologists have found among other forms of life. The Cretaceous world was a highly-dynamic one marked by fluctuating sea levels, the further breakup of continents, and the formation of new mountain ranges. All this moving and shuffling created evolutionary pockets where new species could evolve in relative isolation, becoming restricted to their particular province. Plants proliferated and evolved according to these boundaries just as dinosaurs did.

Each of the pollen provinces, outlined by Vajda and Bercovici, have their own distinctive profile. In northern North America, Asia, and a few spots in South America, Late Cretaceous sediments commonly contain Aquilapollenites – pollen thought to have come from a group of plants closely related to the modern sandalwood. A neighboring province – stretching from eastern North America to the Himalayas – is dominated by pollen from a Cretaceous birch relative, while rocks from the same time in northern South America, central Africa, and India are rife with pollen from palms. Rounding out the set, a southern hemisphere swath has plenty of pollen from plants related to southern beeches and shrubs.

These were not the only plants to exist in those areas, of course, but their pollen broadly delineates differentiated patches. Paleobotanists can zoom in from there, and, as with dinosaurs, the best-studied sites on the planet document the end of the Cretaceous through the beginning of the Paleogene in western North America.

The forests that Tyrannosaurus and Triceratops knew were dominated by angiosperms – flowering plants – with some conifers, ferns, ginkgos, and cycads for good measure. Palm trees stood alongside evergreens and towered above a shrubby understory in these Late Cretaceous forests. In the aftermath of the impact 66 million years ago, however, those forests were replaced by a relatively small collection of angiosperms, a shadow of the diversity that the Edmontosaurus and kin knew.

Plants suffered extinctions just as many other forms of life did. In fact, some of them dwindle to nothing right at the K-Pg boundary are called “K-species” or “K-taxa.” In the pollen record of North America, for example, the sandalwood relative and a suite of species in seven other genera give way to species in just two genera. Overall, about 60% of plant species present in Cretaceous North America went extinct. The rest of the globe reflects a similar pattern, albeit with different species. Many pollen-producing plants either went entirely extinct or became much less abundant.

Clues from the earliest days of the Paleogene track how plant life eventually bounced back. While sites in New Zealand preserve a “fungal spike” from when mushrooms and their ilk thrived on decomposing matter under blacked-out skies, the subsequent “fern spike” records when pioneering plants – primarily ferns – quickly spread as sunlight began to return. The angiosperms, as well as some conifers, followed, but with fewer species than before. Depending on the location, plant life took between one and ten million years to recover to pre-extinction levels of diversity.

As with the animals, though, why some plants went extinct and others persisted is a mystery. Perhaps some were simply lucky enough to grow in places that were less affected by the devastation following the asteroid strike. Then again, Vajda and Bercovici point out, some researchers have suggested that plants carrying additional sets of chromosomes – or were polyploid – might have had the genetic flexibility to more quickly adapt after ecological shock.

Discerning what made a survivor isn’t just an exercise in replaying ancient history, though.

Vajda and Bercovici argue that two previous mass extinctions – roughly 251 and 200 million years ago – follow a similar pattern of a highly-diverse flora being pruned back, followed by crisis species, pioneer communities, and ecosystem recovery in sequence. Which left me to wonder if we’re going to see this pattern again. If  we’re not yet in a Sixth Extinction, we’re close, and identifying likely survivors verses vulnerable species is an essential part of conservation triage. By sifting through the past, down to the tiniest pollen grain, we can reflect on what sort of future we want to create.

Reference:

Vajda, V., Bercovici, A. 2014. The global vegetation pattern across the Cretaceous-Paleogene mass extinction interval: A template for other extinction events. Global and Planetary Change. doi: 10.1016/j.gloplacha.2014.07.014