Kung fu stegosaur: Lethal fighters when necessary

Stegosaurs might be portrayed as lumbering plant eaters, but they were lethal fighters when necessary, according to paleontologists who have uncovered new evidence of a casualty of stegosaurian combat. The evidence is a fatal stab wound in the pubis bone of a predatory allosaur. The wound — in the conical shape of a stegosaur tail spike — would have required great dexterity to inflict and shows clear signs of having cut short the allosaur’s life.

The wound found in the allosaur fits well with what would result from a stegosaur striking under and upwards with its spiked tail. Fossil's of contemporaneous stegosaurs appear to have had unusually flexible and agile tails. Credit: Robert Bakker

The wound found in the allosaur fits well with what would result from a stegosaur striking under and upwards with its spiked tail. Fossil’s of contemporaneous stegosaurs appear to have had unusually flexible and agile tails.
Credit: Robert Bakker

“A massive infection ate away a baseball-sized sector of the bone,” reports Houston Museum of Natural Science paleontologist Robert Bakker and his colleagues, who present a poster on the discovery on Tuesday at the meeting of the Geological Society of America in Vancouver, B.C. “Probably this infection spread upwards into the soft tissue attached here, the thigh muscles and adjacent intestines and reproductive organs.” The lack of any signs of healing strongly suggests the allosaur died from the infection.

Similar wounds are seen in rodeo cowboys or horses when they are gored by longhorns, Bakker said. And since large herbivores — like longhorn cattle, rhinos and buffalo — today defend themselves with horns, it’s reasonable to assume spiky herbivorous dinos did the same. A big difference is that stegosaurs wielded their weapon on their tails rather than their heads. Skeletal evidence from fossil stegosaurs suggests their tails were more dextrous than most dinosaur tails.

“They have no locking joints, even in the tail,” Bakker explained. “Most dinosaur tails get stiffer towards the end.” But stegosaurs had massive muscles at the base of the tails, flexibility and fine muscle control all the way to the tail tip. “The joints of a stegosaur tail look like a monkey’s tail. They were built for 3-dimensional combat.”

In order to deliver the mortal wound to the allosaur, a stegosaur would have had to sweep its tail under the allosaur and twist the tail tip, because normally the spikes point outward and backward. That would have been well within the ability of a stegosaur, Bakker said.

The fighting style and skill of stegosaurs should come as no surprise to anyone familiar with the dinosaur battle scene in the 1940 Disney animated film Fantasia, said Bakker. That segment of the movie shows a beefed up allosaur attacking a stegosaur. The stegosaur delivers a number of well aimed tail blows at the predator, but loses the fight. The Fantasia stegosaur tail dexterity appears to be accurate, he said. But he questions the stegosaur’s loss in the end. “I think the stegosaur threw the fight,” he said. On the other hand, he points out stegosaurs had among the smallest brains for its body size of any large animal, ever.

WFS Dino Diary: Riojasaurus ‭(‬Rioja lizard‭)

Name: Riojasaurus ‭(‬Rioja lizard‭)‬.
Phonetic: Re-o-jah-sore-us.
Named By: Jose Fernando Bonaparte‭ ‬-‭ ‬1967.
Classification: Chordata,‭ ‬Reptilia,‭ ‬Dinosauria,‭ ‬Saurischia,‭ ‬Sauropodomorpha,‭ ‬Prosauropoda,‭ ‬Riojasauridae.
Species: R.‭ ‬incertus‭ (‬type‭)‬.
Diet: Herbivore.
Size: About‭ ‬10‭ ‬meters long.
Known locations: Argentina,‭ ‬La Rioja Province‭ ‬-‭ ‬Los Colorados Formation.
Time period: Norian of the Triassic.
Fossil representation: Several individuals.

       Riojasaurus was and still often is credited as being related to Melanorosaurus,‭ ‬though detailed study of the two genera does turn up some key differences.‭ ‬These two genera are both significant in the development of the prosauropods into the large sauropods common by the late Jurassic in that they are both large and postured so that they were probably obligatory quadrupedal.‭ ‬This is different from other more basal forms of prosauropod that are considered to have been optionally bipedal or quadrupedal,‭ ‬a hallmark of their ancestry from earlier saurischian dinosaurs that seem to have been primarily bipedal.
As a dinosaur,‭ ‬the teeth of Riojasaurus were leaf shaped and serrated hinting at a preference in eating lush leafy vegetation.‭ ‬The scleral rings of the eyes also reveal that Riojasaurus was a cathemeral dinosaur meaning that it was active for short periods during both the day and night.‭ ‬Although the rear limbs were slightly longer than the fore limbs,‭ ‬there was not as huge a difference between them as in some more basal form prosauropod genera,‭ ‬reinforcing the notion that Riojasaurus walked about upon all fours.
Other dinosaurs‭ ‬known from the Los Colorados Formation where Riojasaurus has been found include the‭ ‬sauropodomorphs Coloradisaurus and Lessemsaurus.‭ ‬The theropod Zupaysaurus is also present in a slightly later deposit,‭ ‬though if they did manage to overlap then this dinosaur may have been a predator of smaller juvenile Riojasaurus.

Riojasaurus ‭(‬Rioja lizard‭)

Riojasaurus ‭(‬Rioja lizard‭)

 

Further reading
-‭ ‬Dos nuevas‭ “‬faunas‭” ‬de reptiles triasicos de Argentina‭ [‬Two new reptilian‭ "‬faunas‭" ‬of the Argentine Triassic‭]‬,‭ ‬Jose F.‭ ‬Bonaparte‭ ‬-‭ ‬1967.

-‭ ‬Nocturnality in Dinosaurs Inferred from Scleral Ring and Orbit Morphology,‭ ‬Lars Schmitz‭ & ‬Ryosuke Motani‭ ‬-‭ ‬2011.

Courtesy: PreHistoric Wild life.Com

Bardarbunga volcano sits on massive magma hot spot

Spectacular eruptions at Bárðarbunga volcano in central Iceland have been spewing lava continuously since Aug. 31. Massive amounts of erupting lava are connected to the destruction of supercontinents and dramatic changes in climate and ecosystems.

New research from UC Davis and Aarhus University in Denmark shows that high mantle temperatures miles beneath Earth’s surface are essential for generating such large amounts of magma. In fact, the scientists found that the Bárðarbunga volcano lies directly above the hottest portion of the North Atlantic mantle plume.

The study, published online Oct. 5 and appearing in the November issue of Nature Geoscience, comes from Charles Lesher, professor of Earth and Planetary Science at UC Davis and a visiting professor at Aarhus University, and his former PhD student, Eric Brown, now a post-doctoral scholar at Aarhus University.

Holuhraun fissure eruption on the flanks of the Bárðarbunga volcano in central Iceland on Oct. 4, 2014, showing the development of a lava lake in the foreground. Vapor clouds over the lava lake are caused by degassing of volatile-rich basaltic magma. Credit: Morten S. Riishuus, Nordic Volcanological Institute

Holuhraun fissure eruption on the flanks of the Bárðarbunga volcano in central Iceland on Oct. 4, 2014, showing the development of a lava lake in the foreground. Vapor clouds over the lava lake are caused by degassing of volatile-rich basaltic magma.
Credit: Morten S. Riishuus, Nordic Volcanological Institute

“From time to time the Earth’s mantle belches out huge quantities of magma on a scale unlike anything witnessed in historic times,” Lesher said. “These events provide unique windows into the internal working of our planet.”

Such fiery events have produced large igneous provinces throughout Earth’s history. They are often attributed to upwelling of hot, deeply sourced mantle material, or “mantle plumes.”

Recent models have dismissed the role of mantle plumes in the formation of large igneous provinces, ascribing their origin instead to chemical anomalies in the shallow mantle.

Based on the volcanic record in and around Iceland over the last 56 million years and numerical modeling, Brown and Lesher show that high mantle temperatures are essential for generating the large magma volumes that gave rise to the North Atlantic large igneous provinces bordering Greenland and northern Europe.

Their findings further substantiate the critical role of mantle plumes in forming large igneous provinces.

“Our work offers new tools to constrain the physical and chemical conditions in the mantle responsible for large igneous provinces,” Brown said. “There’s little doubt that the mantle is composed of different types of chemical compounds, but this is not the dominant factor. Rather, locally high mantle temperatures are the key ingredient.”

The research was supported by grants from the US National Science Foundation and by the Niels Bohr Professorship funded by Danish National Research Foundation.

Dinosaur ecology found in fragile amber

Ryan McKellar’s research sounds like it was plucked from Jurassic Park: he studies pieces of amber found buried with dinosaur skeletons. But rather than re-creating dinosaurs, McKellar uses the tiny pieces of fossilized tree resin to study the world in which the now-extinct behemoths lived.

New techniques for investigating very tiny pieces of fragile amber buried in dinosaur bonebeds could close the gaps in knowledge about the ecology of the dinosaurs, said McKellar, who is a research scientist at the Royal Saskatchewan Museum in Saskatchewan, Canada.

“Basically it puts a backdrop to these dinosaur digs, it tells us a bit about the habitat,” said McKellar. The amber can show what kinds of plants were abundant, and what the atmosphere was like at the time the amber was formed, he explained. Scientists can then put together details regarding what kind of habitat the dinosaur lived in and how the bonebed formed.

Photos and drawings of inclusions in Canadian Cretaceous amber from Grassy Lake amber, a 78-79 million year old amber in the Late Cretaceous of southern Alberta. Credit: University of Alberta Strickland Entomology Museum specimen, R.C. McKellar; Chronomyrmex ant Grassy Lake amber, UASM specimen photo; Chronomyrmex ant Grassy Lake amber, UASM specimen drawing

Photos and drawings of inclusions in Canadian Cretaceous amber from Grassy Lake amber, a 78-79 million year old amber in the Late Cretaceous of southern Alberta.
Credit: University of Alberta Strickland Entomology Museum specimen, R.C. McKellar; Chronomyrmex ant Grassy Lake amber, UASM specimen photo; Chronomyrmex ant Grassy Lake amber, UASM specimen drawing

The preliminary findings about dinosaur ecology, habitat, and other results from four different fossil deposits from the Late Cretaceous in Alberta and Saskatchewan, Canada, will be presented on Monday, October 20 at the Geological Society of America Annual Meeting in Vancouver, Canada.

“Just a few of these little pieces among the bones can show a lot of information,” McKellar said.

The type of amber that the scientists work with is not like the jewelry grade variety that can be made into a necklace or earrings.

“This type of amber hasn’t been pursued in the past. It is like working with a shattered candy cane,” he said. It is called friable amber, which is crumbly and fragile.

McKellar and his colleagues work with very small pieces of amber, just millimeters wide. But even samples at such a small scale can hold enormous clues to the past.

Before it hardened into amber, the sticky tree resin would often collect animal and plant material, like leaves and feathers. Scientists call these contents “inclusions,” which they study along with the surrounding amber, to look at environmental conditions, surrounding water sources, temperature, and even oxygen levels in the ancient environment.

Insects can also be included in the amber, which can be even more helpful to scientists. One example is the discovery of an aphid, stuck directly to a duck-billed dinosaur with some amber. With a find like this, scientists can track insect evolution, find their modern relatives, and see how they might have interacted with dinosaurs, said McKellar.

“When you get insects, it is like frosting on the cake — you can really round out the view of the ecosystem.”

Improvements in processing friable amber have made this research possible. Instead of the past technique of screening amber in a glycerin bath, the scientists reduce crumbling by vacuum-injecting the amber with epoxy, said McKellar.

Friable amber is widespread across the North American Continent in association with coals, and in the uncovered bonebeds, which means this area of research has expanded with the new techniques. It means scientists can sample at a finer scale, and still close some gaps in the past, especially regarding insect evolution, said McKellar.

Some of the early results of this method will be presented from amber pieces found with the skeleton of ‘Scotty’ the Tyrannosaurus rex, in Saskatchewan, Canada. McKellar will also be including case studies from three other bonebeds: the Danek Bonebed near Edmonton, Alberta; Dinosaur Provincial Park, Alberta; and the Pipestone Creek Pachyrhinosaurus Bonebed near Grande Prairie, Alberta.

placoderms:Origins of sex discovered?

A profound new discovery announced in Nature today by palaeontologist, Flinders University Professor John Long, reveals how the intimate act of sexual intercourse first evolved in our deep distant ancestors.

In one of the biggest discoveries in the evolutionary history of sexual reproduction, Professor Long has found that internal fertilisation and copulation appeared in ancient armoured fishes, called placoderms, about 385 million years ago in what is now Scotland.

Placoderms, the most primitive jawed vertebrates, are the earliest vertebrate ancestors of humans.

Published in Nature,  the discovery shows that male fossils of the Microbrachius dicki, which belong to the antiarch group of placoderms, developed bony L-shaped genital limbs called claspers to transfer sperm to females; and females developed small paired bones to lock the male organs in place for mating.

Artist's impression of the first act of copulation in our distant ancestors. Credit: Image courtesy of Flinders University

Artist’s impression of the first act of copulation in our distant ancestors.
Credit: Image courtesy of Flinders University

Measuring about 8cm long, Microbrachius lived in ancient lake habitats in Scotland, as well as parts of Estonia and China.

As the paper’s lead author, Professor Long, who is the Strategic Professor in Palaeontology at Flinders University in South Australia, discovered the ancient fishes mating abilities when he stumbled across a single fossil bone in the collections of the University of Technology in Tallinn, Estonia, last year.

The fossils, he said, symbolise the most primitive known vertebrate sexual organ ever found, demonstrating the first use of internal fertilisation and copulation as a reproductive strategy known in the fossil record.

Microbrachius means little arms but scientists have been baffled for centuries by what these bony paired arms were actually there for. We’ve solved this great mystery because they were there for mating, so that the male could position his claspers into the female genital area,” Professor Long said.

“It was previously thought that reproduction spawned externally in water, and much later down the track in the history of vertebrate evolution,” he said.

“Our earlier discoveries published in Nature in 2008 and 2009 of live birth and copulation in placoderms concerned more advanced placoderm groups. Our new discovery now pushes the origin of copulation back even further down the evolutionary ladder, to the most basal of all jawed animals.

“Basically it’s the first branch off the evolutionary tree where these reproductive strategies started.”

In one of the more bizarre findings of his research, Professor Long said the fishes probably copulated from a sideways position with their bony jointed arms locked together.

“This enabled the males to manoeuvre their genital organs into the right position for mating.

“With their arms interlocked, these fish looked more like they are square dancing the do-se-do rather than mating.”

Flinders Postdoctoral Research Fellow Dr Brian Choo, a co-author on the paper, said the discovery signifies the first time in evolutionary history that males and females showed distinct differences in their physical appearance.

“Until this point in evolution, the skeletons of jawed vertebrates couldn’t be distinguished because males and females had the same skeletal structures,” Dr Choo said.

“This is the first time in vertebrate evolution that males and females developed separate reproductive structures, with males developing claspers, and females developing fixed plates to lock the claspers in for mating,” he said.

The discovery highlights the importance of placoderms in the evolution of vertebrate animals, including humans, Professor Long said.

“Placoderms were once thought to be a dead-end group with no live relatives but recent studies show that our own evolution is deeply rooted in placoderms, and that many of the features we have, such as jaws, teeth and paired limbs, first originated with this group of fishes.

“Now, we reveal they gave us the intimate act of sexual intercourse as well.”

Dr Matt Friedman, a palaeobiologist from the University of Oxford, UK, described the discovery as “nothing short of remarkable.”

“Claspers in these fishes demand one of two alternative, but equally provocative, scenarios: either an unprecedented loss of internal fertilisation in vertebrates, or the coherence of the armoured placoderms as a single branch in the tree of life,” Dr Friedman, who was not involved in the study, said.

“Both conclusions fly in the face of received wisdom, and suggest that there is still much to discover about this critical episode in our own extended evolutionary history.”

The research involved a team of collaborators from Australia, Estonia, the UK, Sweden and China, who scrutinised a vast number of fossil specimens held in museum collections across the world.

Fossil specimens of male and female Microbrachius fossils will be placed on public display in the foyer of the South Australian Museum from today (October 20).

A Flinders Creations video documenting the discovery, as well as an animation portraying the earliest known copulation, can be viewed here and here.

Journey to the center of the Earth:Isotope Study

A UC Santa Barbara geochemist studying Samoan volcanoes has found evidence of the planet’s early formation still trapped inside the Earth. Known as hotspots, volcanic island chains such as Samoa can ancient primordial signatures from the early solar system that have somehow survived billions of years.

Matthew Jackson, an associate professor in UCSB’s Department of Earth Science, and colleagues utilized high-precision lead and helium isotope measurements to unravel the chemical composition and geometry of the deep mantle plume feeding Samoa’s volcanoes. Their findings appear today in the journal Nature.

In most cases, volcanoes are located at the point where two tectonic plates meet, and are created when those plates collide or diverge. Hotspot volcanoes, however, are not located at plate boundaries but rather represent the anomalous melting in the interior of the plates.

Such intraplate volcanoes form above a plume-fed hotspot where the Earth’s mantle is melting. The plate moves over time — at approximately the rate human fingernails grow (3 inches a year) — and eventually the volcano moves off the hotspot and becomes extinct. Another volcano forms in its place over the hotspot and the process repeats itself until a string of volcanoes evolves.

“So you end up with this linear trend of age-progressive volcanoes,” Jackson said. “On the Pacific plate, the youngest is in the east and as you go to the west, the volcanoes are older and more deeply eroded. Hawaii has two linear trends of volcanoes — most underwater — which are parallel to each other. There’s a southern trend and a northern trend.”

This map of the Samoan hotspot shows its division into three parallel volcanic lineaments. Credit: UCSB

This map of the Samoan hotspot shows its division into three parallel volcanic lineaments.
Credit: UCSB

Because the volcanic composition of parallel Hawaiian trends is fundamentally different, Jackson and his team decided to look for evidence of this in other hotspots. In Samoa, they found three volcanic trends exhibiting three different chemical configurations as well as a fourth group of a late-stage eruption on top of the third trend of volcanoes. These different groups exhibit distinct compositions.

“Our goal was to figure out how we could use this distribution of volcano compositions at the surface to reverse-engineer how these components are distributed inside this upwelling mantle plume at depth,” Jackson said.

Each of the four distinct geochemical compositions, or endmembers, that the scientists identified in Samoan lavas contained low Helium-3 (He-3) and Helium-4 (He-4) ratios. The surprising discovery was that they all exhibited evidence for mixing with a fifth, rare primordial component consisting of high levels of He-3 and He-4.

“We have really strong evidence that the bulk of the plume is made of the high Helium-3, -4 component,” Jackson said. “That tells us that most of this plume is primordial material and there are other materials hosted inside of this plume with low Helium-3, -4, and these are likely crustal materials sent into the mantle at ancient subduction zones.”

The unique isotopic topology revealed by the researchers’ analysis showed that the four low-helium endmembers do not mix efficiently with one another. However, each of them mixes with the high He-3 and He-4 component.

“This unique set of mixing relationships requires a specific geometry for the four geochemical flavors within the upwelling plume: They must be hosted within a matrix that is composed of the rare fifth component with high He-3,” Jackson explained. “This new constraint on plume structure has important implications for how deep mantle material is entrained in plumes, and it gives us the clearest picture yet for the chemical structure of an upwelling mantle plume.”

Co-authors of the paper include Stanley R. Hart, Jerzy S. Blusztajn and Mark D. Kurz of the Woods Hole Oceanographic Institution, Jasper G. Konter of the University of Hawaii and Kenneth A. Farley of the California Institute of Technology. This research was funded by the National Science Foundation.

Mysterious Midcontinent Rift is a geological hybrid

An international team of geologists has a new explanation for how the Midwest’s biggest geological feature — an ancient and giant 2,000-mile-long underground crack that starts in Lake Superior and runs south to Oklahoma and to Alabama — evolved.

Scientists from Northwestern University, the University of Illinois at Chicago (UIC), the University of Gottingen in Germany and the University of Oklahoma report that the 1.1 billion-year-old Midcontinent Rift is a geological hybrid, having formed in three stages: it started as an enormous narrow crack in the Earth’s crust; that space then filled with an unusually large amount of volcanic rock; and, finally, the igneous rocks were forced to the surface, forming the beautiful scenery seen today in the Lake Superior area of the Upper Midwest.

 

The volcanic rocks of the 1.1 billion-year-old Midcontinent Rift play a prominent role in the natural beauty of Isle Royale National Park in Lake Superior. Credit: Image courtesy of Northwestern University


The volcanic rocks of the 1.1 billion-year-old Midcontinent Rift play a prominent role in the natural beauty of Isle Royale National Park in Lake Superior.
Credit: Image courtesy of Northwestern University

The rift produced some of the Midwest’s most interesting geology and scenery, but there has never been a good explanation for what caused it. Inspired by vacations to Lake Superior, Seth and Carol A. Stein, a husband-and-wife team from Northwestern and UIC, have been determined to learn more in recent years.

Their study, which utilized cutting-edge geologic software and seismic images of rock located below the Earth’s surface in areas of the rift, will be presented Oct. 20 at the Geological Society of America annual meeting in Vancouver.

“The Midcontinent Rift is a very strange beast,” said the study’s lead author, Carol Stein, professor of Earth and Environmental Sciences at UIC. “Rifts are long, narrow cracks splitting the Earth’s crust, with some volcanic rocks in them that rise to fill the cracks. Large igneous provinces, or LIPs, are huge pools of volcanic rocks poured out at the Earth’s surface. The Midcontinent Rift is both of these — like a hybrid animal.”

“Geologists call it a rift because it’s long and narrow,” explained Seth Stein, a co-author of the study, “but it’s got much more volcanic rock inside it than any other rift on a continent, so it’s also a LIP. We’ve been wondering for a long time how this could have happened.” He is the William Deering Professor of Geological Sciences at the Weinberg College of Arts and Sciences.

 

This question is one of those that EarthScope, a major National Science Foundation program involving geologists from across the U.S., seeks to answer. In this case, the team used images of the Earth at depth from seismic experiments across Lake Superior and EarthScope surveys of other parts of the Midcontinent Rift. The images show the rock layers at depth, much as X-ray photos show the bones in people’s bodies.

In reviewing the images, the researchers found the Midcontinent Rift appeared to evolve in three stages.

“First, the rocks were pulled apart, forming a rift valley,” Carol Stein said. “As the rift was pulling apart, magma flowed into the developing crack. After about 10 million years, the crack stopped growing, but more magma kept pouring out on top. Older magma layers sunk under the weight of new magma, so the hole kept deepening. Eventually the magma ran out, leaving a large igneous province — a 20-mile-thick pile of volcanic rocks. Millions of years later, the rift got squeezed as a new supercontinent reassembled, which made the Earth’s crust under the rift thicker.”

To test this idea, the Steins turned to Jonas Kley, professor of geology at Germany’s Gottingen University, their host during a research year in Germany sponsored by the Alexander von Humboldt Foundation.

Kley used software that allows geologic time to run backwards. “We start with the rocks as they are today,” Kley explained, “and then undo movement on faults and vertical movements. It’s like reconstructing a car crash. When we’re done we have a picture of what happened and when. This lets us test ideas and see if they work.”

Kley’s analysis showed that the three-stage history made sense — the Midcontinent Rift started as a rift and then evolved into a large igneous province. The last stage brought rocks in the Lake Superior area to the surface.

Other parts of the picture fit together nicely, the Steins said. David Hindle, also from Gottingen University, used a computer model to show that the rift’s shape seen in the seismic images results from the crust bending under weight of magma.

Randy Keller, a professor and director of the Oklahoma Geological Survey, found that the weight of the dense magma filling the rift explains the stronger pull of gravity measured above the rift. He points out that these variations in the gravity field are the major evidence used to map the extent of the rift.

“It’s funny,” Seth Stein mused. “Carol and I have been living in Chicago for more than 30 years. We often have gone up to Lake Superior for vacations but didn’t think much about the geology. It’s only in the past few years that we realized there’s a great story there and started working on it. There are many studies going on today, which will give more results in the next few years.”

The Steins now are working with other geologists to help park rangers and teachers tell this story to the public. For example, a good way to think about how rifts work is to observe what happens if you pull both ends of a Mars candy bar: the top chocolate layer breaks, and the inside stretches.

“Sometimes people think that exciting geology only happens in places like California,” Seth Stein said. “We hope results like this will encourage young Midwesterners to study geology and make even further advances.”

Microfossils reveal warm oceans had less oxygen

Researchers in Syracuse University’s College of Arts and Sciences are pairing chemical analyses with micropaleontology — the study of tiny fossilized organisms — to better understand how global marine life was affected by a rapid warming event more than 55 million years ago.

Their findings are the subject of an article in the journal Paleoceanography.

“Global warming impacts marine life in complex ways, of which the loss of dissolved oxygen [a condition known as hypoxia] is a growing concern” says Zunli Lu, assistant professor of Earth sciences and a member of Syracuse’s Water Science and Engineering Initiative. “Moreover, it’s difficult to predict future deoxygenation that is induced by carbon emissions, without a good understanding of our geologic past.”

Lu says this type of deoxygenation leads to larger and thicker oxygen minimum zones (OMZs) in the world’s oceans. An OMZ is the layer of water in an ocean where oxygen saturation is at its lowest.

Assistant Professor of Earth Sciences Zunli Lu was among the researchers to release these findings. Credit: Syracuse University

Assistant Professor of Earth Sciences Zunli Lu was among the researchers to release these findings.
Credit: Syracuse University

Much of Lu’s work revolves around the Paleocene-Eocene Thermal Maximum (PETM), a well-studied analogue for modern climate warming. Documenting the expansion of OMZs during the PETM is difficult because of the lack of a sensitive, widely applicable indicator of dissolved oxygen.

To address the problem, Lu and his colleagues have begun working with iodate, a type of iodine that exists only in oxygenated waters. By analyzing the iodine-to-calcium ratios in microfossils, they are able to estimate the oxygen levels of ambient seawater, where microorganisms once lived.

Fossil skeletons of a group of protists known as foraminiferas have long been used for paleo-environmental reconstructions. Developing an oxygenation proxy for foraminifera is important to Lu because it could enable him study the extent of OMZs “in 3-D,” since these popcorn-like organisms have been abundant in ancient and modern oceans.

“By comparing our fossil data with oxygen levels simulated in climate models, we think OMZs were much more prevalent 55 million years ago than they are today,” he says, adding that OMZs likely expanded during the PETM. “Deoxygenation, along with warming and acidification, had a dramatic effect on marine life during the PETM, prompting mass extinction on the seafloor.”

Lu thinks analytical facilities that combine climate modeling with micropaleontology will help scientists anticipate trends in ocean deoxygenation. Already, it’s been reported that modern-day OMZs, such as ones in the Eastern Pacific Ocean, are beginning to expand. “They’re natural laboratories for research,” he says, regarding the interactions between oceanic oxygen levels and climate changes.”

Earliest-known lamprey larva fossils discovered

Few people devote time to pondering the ancient origins of the eel-like lamprey, yet the evolutionary saga of the bloodsucker holds essential clues to the biological roots of humanity.

Today, the Proceedings of the National Academy of Sciences published a description of fossilized lamprey larvae that date back to the Lower Cretaceous — at least 125 million years ago.

They’re the oldest identified fossils displaying the creature in stages of pre-metamorphosis and metamorphosis.

“Among animals with backbones, everything, including us, evolved from jawless fishes,” said Desui Miao, University of Kansas Biodiversity Institute collection manager, who co-authored today’s PNAS paper. “To understand the whole arc of vertebrate evolution, we need to know these animals. The biology of the lamprey holds a molecular clock to date when many evolutionary events occurred.”

(A) This is a photograph of fossil transformer in left view. (B) Photograph of fossil transformer in left view. (C) Box area in B in higher magnification, showing the radials. (D) Photograph and (E) drawing of the head and anterior part of the body of A. (F) Photograph and (G) drawing of the head and anterior part of the body of B. Credit: Proceedings of the National Academy of Sciences

(A) This is a photograph of fossil transformer in left view. (B) Photograph of fossil transformer in left view. (C) Box area in B in higher magnification, showing the radials. (D) Photograph and (E) drawing of the head and anterior part of the body of A. (F) Photograph and (G) drawing of the head and anterior part of the body of B.
Credit: Proceedings of the National Academy of Sciences

Miao said features of the human body come from the jawless fishes, such as the lamprey, a slowly evolving organism — often parasitic — which has inhabited Earth at least since the Devonian, about 400 million years ago.

“For example, a jawless fish such as a lamprey has seven pairs of gill arches, and the anterior pair of these gill arches evolved into our upper and lower jaws,” he said. “Our middle ear bones? They come from the same pair of gill arches.”

Indeed, lamprey evolution sheds light on the development of all animals with a backbone. Because of this, scientists have yearned to discover more history about the stages of the aquatic creature’s three-phased life cycle.

However, lamprey larvae are small and soft, thus seldom fossilized.

“They just don’t have hard parts,” Miao said. “Even fully developed fossil lampreys are rare because they lack skeletons. Most fossil fishes are bony fishes — fish we eat and leave bones on the plate. But lampreys don’t have bones or teeth that can be preserved as fossils.”

Fortunately, during the lush Lower Cretaceous era, freshwater lakes covered Inner Mongolia. These waters were chock-full with the ancestors of today’s lampreys, and many fossils became beautifully preserved in a layer of late-Cretaceous shale, including larvae.

“This type of rock preserves very fine details of fossils,” Miao said. “The same rock preserved evidence of dinosaur feathers from this era. The lamprey larvae were found by local people and some by our Chinese colleagues who specialize in early fishes.”

According to the KU researcher and fellow authors Meemann Chang, Feixiang Wu and Jiangyong Zhang of the Institute of Vertebrate Paleontology and Paleoanthropology at the Chinese Academy of Sciences in Beijing, the larval fossils show the life cycle of the lamprey “emerged essentially in its present mode no later than the Early Cretaceous.”

This cycle consists of a long-lasting larval stage, a metamorphosis and a comparatively brief adulthood with a markedly different anatomy, according to the PNAS paper. The larvae come from the fossil lamprey species Mesomyzon mangae.

“Our larvae look modern,” Miao said. “The developmental stage is almost identical to today’s lamprey. Before this, we didn’t know how long lampreys have developed via metamorphosis. Now, we know it goes back 125 million years at least. In other words, lampreys haven’t changed much — and that’s very interesting.”

Then, like today, lampreys lived in both freshwater and saltwater. At the larval stage, they’d have dwelled in the sand or mud and drawn nutrients from micro-organisms in the water. Then, as mature lampreys, some of them would have subsisted by fastening themselves to host organisms and swigging their blood — often killing their host in the end.

“They attach to larger fish or whales,” Miao said. “They hold on forever.”

The National Basic Research Program of China, the Asian-Swedish Research Partnership Program of the Swedish Research Council and KU Endowment supported this research.

The unexamined diversity in the ‘Coral Triangle’

Research on zoantharians, a group of animals related to corals and anemones, by researchers James Reimer of the University of the Ryukyusin Okinawa, Japan, Angelo Poliseno of Universita Politecnica delle Marchein Italy, and Bert Hoeksema from Naturalis Biodiversity Center, Netherlands, has demonstrated how little we know about marine diversity in the so-called “center of marine biodiversity” located in the central Indo-Pacific Ocean.

The researchers utilized previously collected specimens from Indonesia, the Philippines, Malaysia, and Papua New Guinea, combined with field images from Dr. Hoeksema to examine species of Zoantharia, marine cnidarians commonly found in shallow subtropical and tropical oceans throughout the world. The study was published in the open access journal ZooKeys.

“The central Indo-Pacific is commonly called the “Coral Triangle” due to its high hard coral diversity, in fact the highest in the world” said Reimer, “but in fact for many groups of marine animals we really have little concrete information on diversity, or numbers of species, in this region.”

Previous research included brief reports on a few species of Zoantharia, but until now no formal attempts had been made to list species from this region. Surprisingly, of the 24 potential species identified by the researchers, at least 9 are undescribed.

Much of the work was performed by Dr. Reimer in the Netherlands in 2012, when he visited the Naturalis Museum and Dr. Hoeksema to examine their Zoantharia collection. “What struck me as particularly amazing was the fact that Naturalis housed over 600 Zoantharia specimens collected over the years, and in many cases, even specimens from 1930 had not yet been formally examined,” stated Reimer. “This research demonstrates the real importance of museum collections, as well as the lack of expert researchers for many taxonomic groups.”

“Unfortunately, for many regions of the world, we are only just beginning to examine diversity, despite some of these areas being among the most threatened,” added Reimer. It is hoped future specimen collections will allow further analyses and formal descriptions of these previously unreported species.