Paleontologists at the University of Toronto (U of T) and the Royal Ontario Museum (ROM) in Toronto have entirely revisited a tiny yet exceptionally fierce ancient sea creature called Habelia optata that has confounded scientists since it was first discovered more than a century ago.

The research by lead author Cédric Aria, recent graduate of the PhD program in the department of ecology & evolutionary biology in the Faculty of Arts & Science at U of T, and co-author Jean-Bernard Caron, senior curator of invertebrate palaeontology at the ROM and an associate professor in the departments of ecology & evolutionary biology and Earth sciences at U of T, is published today in BMC Evolutionary Biology.

Approximately 2 cm in length with a tail as long as the rest of its body, the long-extinct Habelia optata belongs to the group of invertebrate animals called arthropods, which also includes such familiar creatures as spiders, insects, lobsters and crabs. It lived during the middle Cambrian period approximately 508 million years ago and comes from the renowned Burgess Shale fossil deposit in British Columbia. Habelia optata was part of the “Cambrian explosion,” a period of rapid evolutionary change when most major animal groups first emerged in the fossil record.

Like all arthropods, Habelia optata features a segmented body with external skeleton and jointed limbs. What remained unclear for decades, however, was the main sub-group of arthropods to which Habelia belonged. Early studies had mentioned mandibulates — a hyperdiverse lineage whose members possess antennae and a pair of specialized appendages known as mandibles, usually used to grasp, squeeze and crush their food. But Habelia was later left as one of the typically unresolved arthropods of the Burgess Shale.

The new analysis by the U of T-ROM researchers suggests that Habelia optata was instead a close relative of the ancestor of all chelicerates, the other sub-group of arthropods living today, named for the presence of appendages called chelicerae in front of the mouth and used to cut food. This is mostly due to the overall anatomy of the head in Habelia, and the presence of two small chelicerae-like appendages revealed in these fossils.

“Habelia now shows in great detail the body architecture from which chelicerates emerged, which allows us to solve some long-standing questions,” said Aria, who is now a post-doctoral researcher at the Nanjing Institute of Geology and Palaeontology, in China. “We can now explain why, for instance, horseshoe crabs have a reduced pair of limbs — the chilaria — at the back of their heads. Those are relics of fully-formed appendages, as chelicerates seem to originally have had heads with no less than seven pairs of limbs.”

Aria and Caron analyzed 41 specimens in total, the majority of which are new specimens acquired by ROM-led fieldwork parties to the Burgess Shale.

The research illustrates that the well-armoured body of Habelia optata, covered in a multitude of different spines, was divided into head, thorax and post-thorax, all bearing different types of appendages. The thorax displays five pairs of walking legs, while the post-thorax houses rounded appendages likely used in respiration.

“Scorpions and the now-extinct sea scorpions are also chelicerates with bodies divided into three distinct regions,” Aria explained. “We think that these regions broadly correspond to those of Habelia. But a major difference is that scorpions and sea scorpions, like all chelicerates, literally ‘walk on their heads,’ while Habelia still had walking appendages in its thorax.”

The researchers argue that this difference in anatomy allowed Habelia to evolve an especially complex head that makes this fossil species even more peculiar compared to known chelicerates. The head of Habelia contained a series of five appendages made of a large plate with teeth for mastication, a leg-like branch with stiff bristle-like spines for grasping, and an elongate, slender branch modified as a sensory or tactile appendage.

“This complex apparatus of appendages and jaws made Habelia an exceptionally fierce predator for its size,” said Aria. “It was likely both very mobile and efficient in tearing apart its preys.”

The surprising outcome of this study, despite the evolutionary relationship of Habelia with chelicerates, is that these unusual characteristics led instead the researchers to compare the head of Habelia with that of mandibulates from a functional perspective. Thus, the peculiar sensory branches may have been used in a similar fashion as mandibulates use antennae. Also, the overlapping plate-like appendages in the middle series of five are shown to open and close parallel to the underside of the head — much as they do in mandibulates, especially those that feed on animals with hardened carapaces.

Lastly, a seventh pair of appendages at the back of the head seems to have fulfilled a function similar to that of “maxillipeds” — appendages in mandibulates that assist with the other head limbs in the processing of food. This broad correspondence in function rather than in evolutionary origin is called “convergence.”

“From an evolutionary point of view, Habelia is close to the point of divergence between chelicerates and mandibulates,” Aria said. “But its similarities with mandibulates are secondary modifications of features that were in part already chelicerate in nature. This suggests that chelicerates originated from species with a high structural variability.”

The researchers conclude from the outstanding head structure, as well as from well-developed walking legs, that Habelia optata and its relatives were active predators of the Cambrian sea floors, hunting for small shelly sea creatures, such as small trilobites — arthropods with hard, mineralized exoskeletons that were already very diverse and abundant during Cambrian times.

“This builds onto the importance of carapaces and shells for evolutionary change during the Cambrian explosion, and expands our understanding of ecosystems at this time, showing another level of predator-prey relationship and its determining impact on the rise of arthropods as we know them today,” said Caron, who was Aria’s PhD supervisor when the bulk of this research was completed.

“The appearance and spread of animals with shells are considered to be one of the defining characteristics of the Cambrian explosion, and Habelia contributes to illustrate how important this ecological factor was for the early diversification of chelicerates and arthropods in general.”

Reference:
Cédric Aria, Jean-Bernard Caron. Mandibulate convergence in an armoured Cambrian stem chelicerate. BMC Evolutionary Biology, 2017; 17 (1) DOI: 10.1186/s12862-017-1088-7

Note: The above post is reprinted from materials provided by University of Toronto.

A new dolphin species likely from the Oligocene was discovered and described in Ecuador, according to a study published December 20, 2017 in the open-access journal PLOS ONE by Yoshihiro Tanaka from the Osaka Museum of Natural History, Japan, and colleagues.

Many marine fossils described in previous research have been from long-recognized temperate regions such as South Carolina, off the coast of Oregon, Hokkaido and New Zealand. Few equatorial and polar fossils are currently known.

While in the tropical region of Santa Elena Province, Ecuador, the authors of this study found a small dolphin skull, which they identified as representing a new species, Urkudelphis chawpipacha, based on facial features. The dolphin skull had a bone crest front and center on its face, above the eye sockets. This species stands apart from other Oligocene dolphins with its shorter and wider frontal bones located near the top of the head and the parallel-sided posterior part of its jaw. The authors also conducted a phylogenetic analysis which revealed that the new species may be the ancestor of the nearly-extinct Platanistoidea, or river dolphin, and may have lived during the Oligocene era.

The fossil is one of the few fossil dolphins from the equator, and is a reminder that Oligocene cetaceans may have ranged widely in tropical waters.

Reference:
A new tropical Oligocene dolphin from Montañita/Olón, Santa Elena, Ecuador. DOI: 10.1371/journal.pone.0188380

Note: The above post is reprinted from materials provided by PLOS.

A team of researchers from Uppsala University have uncovered a hidden diversity of microscopic animal fossils from over half a billion years ago lurking in rocks from the northern tip of Greenland.

The Cambrian explosion of animal diversity beginning ~541 million years ago is a defining episode in the history of life. This was a time when the seas first teemed with animal life, and the first recognisably modern ecosystems began to take shape.

Current accounts of this explosion in animal diversity rely heavily on records from fossilised shells and other hard parts, since these structures are the most likely to survive as fossils.

However, since most marine animals are soft-bodied this represents only a small fraction of the total diversity.

Rare sites of exceptional fossilisation, like the world-famous Burgess Shale, have revolutionised palaeontologists understanding of soft-bodied Cambrian life. Because of the special conditions of fossilisation at these localities, organisms that did not produce hard mineralized shells or skeletons are also preserved. Such sites offer a rare glimpse into the true diversity of these ancient seas, which were filled with a dazzling array of soft and squishy predatory worms and arthropods (the group containing modern crustaceans and insects).

One of the oldest of these truly exceptional fossil bonanzas is the Sirius Passet site in the far north of Greenland. Unfortunately, during their long history, the rocks at Sirius Passet have been heated up and baked to high temperatures as the northern margin of Greenland smashed into various tectonic plates and buried these rocks deep beneath the surface.

All this heating has boiled away the delicate organic remains that once formed the fossils of soft bodied animals at Sirius Passet, leaving only faint impressions of their remains.

Not far to the south of Sirius Passet, the rocks have escaped the worst effects of this heating. A team of palaeontologists from Uppsala (Ben Slater, Sebastian Willman, Graham Budd and John Peel) used a low-manipulation acid extraction procedure to dissolve some of these less intensively cooked mudrocks. To their astonishment, this simple preparation technique revealed a wealth of previously unknown microscopic animal fossils preserved in spectacular detail.

Most of the fossils were less than a millimetre long and had to be studied under the microscope. Fossils at the nearby Sirius Passet site typically preserve much larger animals, so the new finds fill an important gap in our knowledge of the small-scale animals that probably made up the majority of these ecosystems. Among the discoveries were the tiny spines and teeth of priapulid worms – small hook shaped structures that allowed these worms to efficiently burrow through the sediments and capture prey. Other finds included the tough outer cuticles and defensive spines of various arthropods, and perhaps most surprisingly, microscopic fragments of the oldest known pterobranch hemichordates – an obscure group of tube-dwelling filter feeders that are distant relatives of the vertebrates. This group became very diverse after the Cambrian Period and are among some of the most commonly found fossils in rocks from younger deposits, but were entirely unknown from the early Cambrian. This new source of fossils will also help palaeontologists to better understand the famously difficult to interpret fossils at the nearby Sirius Passet site, where the flattened animal fossils are usually complete, but missing crucial microscopic details.

“The sheer abundance of these miniature animal fossils means that we have only begun to scratch the surface of this overlooked resource, but it is already clear that this discovery will help to reshape our view of the non-shelly animals that crawled and swam among the early Cambrian seas more than half a billion years ago,” says Sebastian Willman, researcher at the Department of Earth Sciences, Uppsala University.

Reference:
Ben J. Slater et al. Widespread preservation of small carbonaceous fossils (SCFs) in the early Cambrian of North Greenland, Geology (2017). DOI: 10.1130/G39788.1

Note: The above post is reprinted from materials provided by Uppsala University.

Researchers at UCLA and the University of Wisconsin-Madison have confirmed that microscopic fossils discovered in a nearly 3.5 billion-year-old piece of rock in Western Australia are the oldest fossils ever found and indeed the earliest direct evidence of life on Earth.

The study, published today in the Proceedings of the National Academy of Sciences, was led by J. William Schopf, professor of paleobiology at UCLA, and John W. Valley, professor of geoscience at the University of Wisconsin-Madison. The research relied on new technology and scientific expertise developed by researchers in the UW-Madison WiscSIMS Laboratory.

The study describes 11 microbial specimens from five separate taxa, linking their morphologies to chemical signatures that are characteristic of life. Some represent now-extinct bacteria and microbes from a domain of life called Archaea, while others are similar to microbial species still found today. The findings also suggest how each may have survived on an oxygen-free planet.

The microfossils—so called because they are not evident to the naked eye—were first described in the journal Science in 1993 by Schopf and his team, which identified them based largely on the fossils’ unique, cylindrical and filamentous shapes. Schopf, director of UCLA’s Center for the Study of Evolution and the Origin of Life, published further supporting evidence of their biological identities in 2002.

He collected the rock in which the fossils were found in 1982 from the Apex chert deposit of Western Australia, one of the few places on the planet where geological evidence of early Earth has been preserved, largely because it has not been subjected to geological processes that would have altered it, like burial and extreme heating due to plate-tectonic activity.

But Schopf’s earlier interpretations have been disputed. Critics argued they are just odd minerals that only look like biological specimens. However, Valley says, the new findings put these doubts to rest; the microfossils are indeed biological.

“I think it’s settled,” he says.

Using a secondary ion mass spectrometer (SIMS) at UW-Madison called IMS 1280—one of just a handful of such instruments in the world—Valley and his team, including department geoscientists Kouki Kitajima and Michael Spicuzza, were able to separate the carbon composing each fossil into its constituent isotopes and measure their ratios.

Isotopes are different versions of the same chemical element that vary in their masses. Different organic substances—whether in rock, microbe or animal—contain characteristic ratios of their stable carbon isotopes.

Using SIMS, Valley’s team was able to tease apart the carbon-12 from the carbon-13 within each fossil and measure the ratio of the two compared to a known carbon isotope standard and a fossil-less section of the rock in which they were found.

“The differences in carbon isotope ratios correlate with their shapes,” Valley says. “If they’re not biological there is no reason for such a correlation. Their C-13-to-C-12 ratios are characteristic of biology and metabolic function.”

Based on this information, the researchers were also able to assign identities and likely physiological behaviors to the fossils locked inside the rock, Valley says. The results show that “these are a primitive, but diverse group of organisms,” says Schopf.

The team identified a complex group of microbes: phototrophic bacteria that would have relied on the sun to produce energy, Archaea that produced methane, and gammaproteobacteria that consumed methane, a gas believed to be an important constituent of Earth’s early atmosphere before oxygen was present.

It took Valley’s team nearly 10 years to develop the processes to accurately analyze the microfossils—fossils this old and rare have never been subjected to SIMS analysis before. The study builds on earlier achievements at WiscSIMS to modify the SIMS instrument, to develop protocols for sample preparation and analysis, and to calibrate necessary standards to match as closely as possible the hydrocarbon content to the samples of interest.

In preparation for SIMS analysis, the team needed to painstakingly grind the original sample down as slowly as possible to expose the delicate fossils themselves—all suspended at different levels within the rock and encased in a hard layer of quartz—without actually destroying them. Spicuzza describes making countless trips up and down the stairs in the department as geoscience technician Brian Hess ground and polished each microfossil in the sample, one micrometer at a time.

Each microfossil is about 10 micrometers wide; eight of them could fit along the width of a human hair.

Valley and Schopf are part of the Wisconsin Astrobiology Research Consortium, funded by the NASA Astrobiology Institute, which exists to study and understand the origins, the future and the nature of life on Earth and throughout the universe.

Studies such as this one, Schopf says, indicate life could be common throughout the universe. But importantly, here on Earth, because several different types of microbes were shown to be already present by 3.5 billion years ago, it tells us that “life had to have begun substantially earlier—nobody knows how much earlier—and confirms it is not difficult for primitive life to form and to evolve into more advanced microorganisms,” says Schopf.

Earlier studies by Valley and his team, dating to 2001, have shown that liquid water oceans existed on Earth as early as 4.3 billion years ago, more than 800 million years before the fossils of the present study would have been alive, and just 250 million years after the Earth formed.

“We have no direct evidence that life existed 4.3 billion years ago but there is no reason why it couldn’t have,” says Valley. “This is something we all would like to find out.”

UW-Madison has a legacy of pushing back the accepted dates of early life on Earth. In 1953, the late Stanley Tyler, a geologist at the university who passed away in 1963 at the age of 57, was the first person to discover microfossils in Precambrian rocks. This pushed the origins of life back more than a billion years, from 540 million to 1.8 billion years ago.

“People are really interested in when life on Earth first emerged,” Valley says. “This study was 10 times more time-consuming and more difficult than I first imagined, but it came to fruition because of many dedicated people who have been excited about this since day one … I think a lot more microfossil analyses will be made on samples of Earth and possibly from other planetary bodies.”

Reference:
J. William Schopf el al., “SIMS analyses of the oldest known assemblage of microfossils document their taxon-correlated carbon isotope compositions,” PNAS (2017). DOI: 10.1073/pnas.1718063115

Note: The above post is reprinted from materials provided by University of Wisconsin-Madison.

A new analysis of the oldest known fossil microorganisms provides strong evidence to support an increasingly widespread understanding that life in the universe is common.

The microorganisms, from Western Australia, are 3.465 billion years old. Scientists from UCLA and the University of Wisconsin-Madison report today in the journal Proceedings of the National Academy of Sciences that two of the species they studied appear to have performed a primitive form of photosynthesis, another apparently produced methane gas, and two others appear to have consumed methane and used it to build their cell walls.

The evidence that a diverse group of organisms had already evolved extremely early in the Earth’s history — combined with scientists’ knowledge of the vast number of stars in the universe and the growing understanding that planets orbit so many of them — strengthens the case for life existing elsewhere in the universe because it would be extremely unlikely that life formed quickly on Earth but did not arise anywhere else.

“By 3.465 billion years ago, life was already diverse on Earth; that’s clear — primitive photosynthesizers, methane producers, methane users,” said J. William Schopf, a professor of paleobiology in the UCLA College, and the study’s lead author. “These are the first data that show the very diverse organisms at that time in Earth’s history, and our previous research has shown that there were sulfur users 3.4 billion years ago as well.

“This tells us life had to have begun substantially earlier and it confirms that it was not difficult for primitive life to form and to evolve into more advanced microorganisms.”

Schopf said scientists still do not know how much earlier life might have begun.

“But, if the conditions are right, it looks like life in the universe should be widespread,” he said.

The study is the most detailed ever conducted on microorganisms preserved in such ancient fossils. Researchers led by Schopf first described the fossils in the journal Science in 1993, and then substantiated their biological origin in the journal Nature in 2002. But the new study is the first to establish what kind of biological microbial organisms they are, and how advanced or primitive they are.

For the new research, Schopf and his colleagues analyzed the microorganisms with cutting-edge technology called secondary ion mass spectroscopy, or SIMS, which reveals the ratio of carbon-12 to carbon-13 isotopes — information scientists can use to determine how the microorganisms lived. (Photosynthetic bacteria have different carbon signatures from methane producers and consumers, for example.) In 2000, Schopf became the first scientist to use SIMS to analyze microscopic fossils preserved in rocks; he said the technology will likely be used to study samples brought back from Mars for signs of life.

The Wisconsin researchers, led by geoscience professor John Valley, used a secondary ion mass spectrometer — one of just a few in the world — to separate the carbon from each fossil into its constituent isotopes and determine their ratios.

“The differences in carbon isotope ratios correlate with their shapes,” Valley said. “Their C-13-to-C-12 ratios are characteristic of biology and metabolic function.”

The fossils were formed at a time when there was very little oxygen in the atmosphere, Schopf said. He thinks that advanced photosynthesis had not yet evolved, and that oxygen first appeared on Earth approximately half a billion years later before its concentration in our atmosphere increased rapidly starting about 2 billion years ago.

Oxygen would have been poisonous to these microorganisms, and would have killed them, he said.

Primitive photosynthesizers are fairly rare on Earth today because they exist only in places where there is light but no oxygen — normally there is abundant oxygen anywhere there is light. And the existence of the rocks the scientists analyzed is also rather remarkable: The average lifetime of a rock exposed on the surface of the Earth is about 200 million years, Schopf said, adding that when he began his career, there was no fossil evidence of life dating back farther than 500 million years ago.

“The rocks we studied are about as far back as rocks go.”

While the study strongly suggests the presence of primitive life forms throughout the universe, Schopf said the presence of more advanced life is very possible but less certain.

One of the paper’s co-authors is Anatoliy Kudryavtsev, a senior scientist at UCLA’s Center for the Study of Evolution and the Origin of Life, of which Schopf is director. The research was funded by the NASA Astrobiology Institute.

In May 2017, a paper in PNAS by Schopf, UCLA graduate student Amanda Garcia and colleagues in Japan showed the Earth’s near-surface ocean temperature has dramatically decreased over the past 3.5 billion years. The work was based on their analysis of a type of ancient enzyme present in virtually all organisms.

In, 2015 Schopf was part of an international team of scientists that described in PNAS their discovery of the greatest absence of evolution ever reported — a type of deep-sea microorganism that appears not to have evolved over more than 2 billion years.

Reference:
J. William Schopf, Kouki Kitajima, Michael J. Spicuzza, Anatoliy B. Kudryavtsev, John W. Valley. SIMS analyses of the oldest known assemblage of microfossils document their taxon-correlated carbon isotope compositions. Proceedings of the National Academy of Sciences, 2017; 201718063 DOI: 10.1073/pnas.1718063115

Note: The above post is reprinted from materials provided by University of California – Los Angeles.

Researchers from the Canadian Museum of Nature and the Natural History Museum of Los Angeles County have identified remains of a 3.5-million-year-old bear from a fossil-rich site in Canada’s High Arctic. Their study shows not only that the animal is a close relative of the ancestor of modern bears — tracing its ancestry to extinct bears of similar age from East Asia — but that it also had a sweet tooth, as determined by cavities in the teeth.

The scientists identify the bear as Protarctos abstrusus, which was previously only known from a tooth found in Idaho. Showing its transitional nature, the animal was slightly smaller than a modern black bear, with a flatter head and a combination of primitive and advanced dental characters. The results are published today in the journal Scientific Reports.

“This is evidence of the most northerly record for primitive bears, and provides an idea of what the ancestor of modern bears may have looked like,” says Dr. Xiaoming Wang, lead author of the study and Head of Vertebrate Paleontology at the Natural History Museum of Los Angeles County (NHMLA). “Just as interesting is the presence of dental caries, showing that oral infections have a long evolutionary history in the animals, which can tell us about their sugary diet, presumably from berries. This is the first and earliest documented occurrence of high-calorie diet in basal bears, likely related to fat storage in preparation for the harsh Arctic winters.”

The research team, which included co-author Dr. Natalia Rybczynski, a Research Associate and paleontologist with the Canadian Museum of Nature, were able to study recovered bones from the skull, jaws and teeth, as well as parts of the skeleton from two individuals.

The bones were discovered over a 20-year period by Canadian Museum of Nature scientists, including Dr. Rybczynski, at a fossil locality on Ellesmere Island known as the Beaver Pond site. The peat deposits include fossilized plants indicative of a boreal-type wetland forest, and have yielded other fossils, including fish, beaver, small carnivores, deerlets, and a three-toed horse.

The findings show that the Ellesmere Protarctos lived in a northern boreal-type forest habitat, where there would have been 24-hour darkness in winter, as well as about six months of ice and snow.

“It is a significant find, in part because all other ancient fossil ursine bears, and even some modern bear species like the sloth bear and sun bear, are associated with lower-latitude, milder habitats,” says co-author Dr. Rybczynski. “So, the Ellesmere bear is important because it suggests that the capacity to exploit the harshest, most northern forests on the planet is not an innovation of modern grizzlies and black bears, but may have characterized the ursine lineage from its beginning.”

Dr. Wang analyzed characteristics of fossil bear remains from around the world to identify the Ellesmere remains as Protarctos and to establish its evolutionary lineage in relation to other bears. Modern bears are wide-ranging, found from equatorial to polar regions. Their ancestors, mainly found in Eurasia, date to about 5 million years ago.

Fossil records of ursine bears (all living bears plus their ancestors, except the giant panda, which is an early offshoot) are poor and their early evolution controversial. The new fossil represents one of the early immigrations from Asia to North America but it is probably not a direct ancestor to the modern American black bear.

Of further significance is that the teeth of both Protarctos individuals show signs of well-developed dental cavities, which were identified following CT scans by Stuart White, a retired professor with the UCLA School of Dentistry. The cavities underline that these ancient bears consumed large amounts of sugary foods such as berries. Indeed, berry plants are found preserved in the same Ellesmere deposits as the bear remains.

“We know that modern bears consume sugary fruits in the fall to promote fat accumulation that allows for winter survival via hibernation. The dental cavities in Protarctos suggest that consumption of sugar-rich foods like berries, in preparation for winter hibernation, developed early in the evolution of bears as a survival strategy,” explains Rybczynski.

Reference:
Xiaoming Wang, Natalia Rybczynski, C. Richard Harington, Stuart C. White, Richard H. Tedford. A basal ursine bear (Protarctos abstrusus) from the Pliocene High Arctic reveals Eurasian affinities and a diet rich in fermentable sugars. Scientific Reports, 2017; 7 (1) DOI: 10.1038/s41598-017-17657-8

Note: The above post is reprinted from materials provided by Natural History Museum of Los Angeles County.

Fossils from New Zealand have revealed a giant penguin that was as big as a grown man, roughly the size of the captain of the Pittsburgh Penguins.

The creature was slightly shorter in length and about 20 pounds (9 kilograms) heavier than the official stats for hockey star Sidney Crosby. It measured nearly 5 feet, 10 inches (1.77 meters) long when swimming and weighed in at 223 pounds (101 kilograms).

If the penguin and the Penguin faced off on the ice, however, things would look different. When standing, the ancient bird was maybe only 5-foot-3 (1.6 meters).

The newly found bird is about 7 inches (18 centimeters) longer than any other ancient penguin that has left a substantial portion of a skeleton, said Gerald Mayr of the Senckenberg Research Institute and Natural History Museum in Frankfurt, Germany. A potentially bigger rival is known only from a fragment of leg bone, making a size estimate difficult.

The biggest penguin today, the emperor in Antarctica, stands less than 4 feet (1.2 meters) tall.

Mayr and others describe the giant creature in a paper released Tuesday by the journal Nature Communications. They named it Kumimanu biceae, which refers to Maori words for a large mythological monster and a bird, and the mother of one of the study’s authors. The fossils are 56 million to 60 million years old.

That’s nearly as old as the very earliest known penguin fossils, which were much smaller, said Daniel Ksepka, curator at the Bruce Museum of Greenwich, Connecticut. He has studied New Zealand fossil penguins but didn’t participate in the new study.

The new discovery shows penguins “got big very rapidly” after the mass extinction of 66 million years ago that’s best known for killing off the dinosaurs, he wrote in an email.

That event played a big role in penguin history. Beforehand, a non-flying seabird would be threatened by big marine reptile predators, which also would compete with the birds for food. But once the extinction wiped out those reptiles, the ability to fly was not so crucial, opening the door for penguins to appear.

Birds often evolve toward larger sizes after they lose the ability to fly, Mayr said. In fact, the new paper concludes that big size appeared more than once within the penguin family tree.

What happened to the giants?

Mayr said researchers believe they died out when large marine mammals like toothed whales and seals showed up and provided competition for safe breeding places and food. The newcomers may also have hunted the big penguins, he said.

Reference:
Gerald Mayr et al. A Paleocene penguin from New Zealand substantiates multiple origins of gigantism in fossil Sphenisciformes, Nature Communications (2017). DOI: 10.1038/s41467-017-01959-6

Note: The above post is reprinted from materials provided by The Associated Press.