New species of tiny tyrannosaur foreshadows rise of T. rex
A newly discovered, diminutive — by T. rexstandards — relative of the tyrant king of dinosaurs reveals crucial new information about when and how T. rex came to rule the North American roost.
Meet Moros intrepidus, a small tyrannosaur who lived about 96 million years ago in the lush, deltaic environment of what is now Utah during the Cretaceous period. The tyrannosaur, whose name means “harbinger of doom,” is the oldest Cretaceous tyrannosaur species yet discovered in North America, narrowing a 70-million-year gap in the fossil record of tyrant dinosaurs on the continent.
“With a lethal combination of bone-crunching bite forces, stereoscopic vision, rapid growth rates, and colossal size, tyrant dinosaurs reigned uncontested for 15 million years leading up to the end-Cretaceous extinction — but it wasn’t always that way,” says Lindsay Zanno, paleontologist at North Carolina State University, head of paleontology at the North Carolina Museum of Sciences and lead author of a paper describing the research. “Early in their evolution, tyrannosaurs hunted in the shadows of archaic lineages such as allosaurs that were already established at the top of the food chain.”
Medium-sized, primitive tyrannosaurs have been found in North America dating from the Jurassic (around 150 million years ago). By the Cretaceous — around 81 million years ago — North American tyrannosaurs had become the enormous, iconic apex predators we know and love. The fossil record between these time periods has been a blank slate, preventing scientists from piecing together the story behind the ascent of tyrannosaurs in North America. “When and how quickly tyrannosaurs went from wallflower to prom king has been vexing paleontologists for a long time,” says Zanno. “The only way to attack this problem was to get out there and find more data on these rare animals.”
That’s exactly what Zanno and her team did. A decade spent hunting for dinosaur remains within rocks deposited at the dawn of the Late Cretaceous finally yielded teeth and a hind limb from the new tyrannosaur. In fact, the lower leg bones of Moros were discovered in the same area where Zanno had previously found Siats meekerorum, a giant meat-eating carcharodontosaur that lived during the same period. Moros is tiny by comparison — standing only three or four feet tall at the hip, about the size of a modern mule deer. Zanno estimates that the Moros was over seven years old when it died, and that it was nearly full-grown.
But don’t let the size fool you. “Moros was lightweight and exceptionally fast,” Zanno says. “These adaptations, together with advanced sensory capabilities, are the mark of a formidable predator. It could easily have run down prey, while avoiding confrontation with the top predators of the day.
“Although the earliest Cretaceous tyrannosaurs were small, their predatory specializations meant that they were primed to take advantage of new opportunities when warming temperatures, rising sea-level and shrinking ranges restructured ecosystems at the beginning of the Late Cretaceous,” Zanno says. “We now know it took them less than 15 million years to rise to power.”
The bones of Moros also revealed the origin of T. rex’s lineage on the North American continent. When the scientists placed Moroswithin the family tree of tyrannosaurs they discovered that its closest relatives were from Asia. “T. rex and its famous contemporaries such as Triceratops may be among our most beloved cultural icons, but we owe their existence to their intrepid ancestors who migrated here from Asia at least 30 million years prior,” Zanno says. “Moros signals the establishment of the iconic Late Cretaceous ecosystems of North America.”
The research appears in Communications Biology, and was supported in part by Canyonlands Natural History Association. Lecturer Terry Gates, postdoctoral research scholar Aurore Canoville and graduate student Haviv Avrahami from NC State, as well as the Field Museum’s Peter Makovicky and Ryan Tucker from Stellenbosch University, contributed to the work.
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Half-a-billion-year-old weird wonder worm finally gets its place in the tree of life
Amiskwia was originally described by the famous palaeontologist Charles Doolittle Walcott (1850-1927) in 1911 who compared it to the modern arrow worms (chaetognaths) — a group of ocean-dwelling worms that are fierce predators, equipped with an array of spines on their head for grasping small prey.
Such organisms are found world-wide at sites like the famous Burgess Shale in the Canadian Rockies, where their soft bodies are preserved intact.
The strange anatomies exhibited by these animals led the American palaeontologist Stephen Jay Gould (1941-2002) to speculate that these organisms represented extinct body plans that are no longer seen today and that if we were to wind back the clocks to the Cambrian, more than 500-million-years-ago, and re-run the tape of life, then perhaps the animals alive today would look very different.
More than 50 years after Doolittle Walcott came up with his theory about Amiskwia, scientists investigated its affinities and rejected his interpretation as they could not find evidence of the canonical grasping spines.
Instead, they suggested it could be a ribbon worm, or its own distinct lineage only distantly related to anything that resembles it today.
When Dr Jakob Vinther from the University of Bristol’s Schools of Earth Sciences and Biological Sciences and Luke Parry, now at Yale University, studied specimens of Amiskwia, kept at the Smithsonian Institution they found something that had been missed before.
Dr Vinther said: “I coated the specimen with ammonium chloride smoke to make the relief of the fossil stand out and then I could see that in the head was a pair of robust elements.”
Interpreting these structures as a set of jaws, their resemblance led him to think of a group of animals, called gnathiferans, which include rotifers, gnathostomulids and micrognathozoans. These animals are microscopic worms, with a distinctive internal jaw apparatus.
The scientists realised that Amiskwia suddenly had a jaw of a gnathiferan, but a body of an arrow worm.
Dr Vinther said: “The bizarre combination of anatomy seemed altogether alien back in 2012.
“Some people have proposed that there could be a relationship between arrow worms and gnathiferans based on their shared possession of a jaw apparatus, both made of a substance called chitin.
“However, there was little other evidence to suggest a relationship, such as evidence from phylogenetic analyses of DNA.”
Luke Parry added: “It altogether seemed like heresy to propose that gnathiferans and arrow worms may be related back then so we held off publishing our intriguing results out of fear of criticism from our peers.
“However, new DNA studies have since emerged that found arrow worms to be more and more closely affiliated to the Gnathifera in the Tree of Life.
“In particular, some researchers found that arrow worms share a duplication of the important Hox genes with a gnathiferan, the rotifers. We suddenly felt no more in a deadlock situation.”
Now the authors have published their findings in the journal Current Biology. The study follows a new phylogenetic study, which finds robust support for arrow worms forming an evolutionary group with gnathiferans.
Luke Parry said: “We were excited to see that these researchers found a relationship between arrow worms and rotifers.
“Our phylogenetic analysis, based on anatomical features, strongly suggest a relationship between these two groups of animals as well.”
The researchers find that Amiskwia is a stem lineage to arrow worms that possess the jaw apparatus seen in gnathiferan worms.
This jaw evolved into the fearsome grasping spines in living arrow worms, which now is an important link in the marine food chain. Small crustacean larvae have evolved long protective spines to protect themselves from being swallowed by arrow worms.
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Marsupial lived among Arctic dinosaurs
A research team has discovered a previously unknown species of marsupial that lived in Alaska’s Arctic during the era of dinosaurs, adding a vivid new detail to a complex ancient landscape.
The thumb-sized animal, named Unnuakomys hutchisoni, lived in the Arctic about 69 million years ago during the late Cretaceous Period. Its discovery, led by scientists from the University of Colorado and University of Alaska Fairbanks, is outlined in an article published in the Journal of Systematic Palaeontology.
The discovery adds to the picture of an environment that scientists say was surprisingly diverse. The tiny animal, which is the northernmost marsupial ever discovered, lived among a unique variety of dinosaurs, plants and other animals.
Alaska’s North Slope, which was at about 80 degrees north latitude when U. hutchisoni lived there, was once thought to be a barren environment during the late Cretaceous. That perception has gradually changed since dinosaurs were discovered along the Colville River in the 1980s, with new evidence showing the region was home to a diverse collection of unique species that didn’t exist anywhere else.
Finding a new marsupial species in the far north adds a new layer to that evolving view, said Patrick Druckenmiller, the director of the University of Alaska Museum of the North.
“Northern Alaska was not only inhabited by a wide variety of dinosaurs, but in fact we’re finding there were also new species of mammals that helped to fill out the ecology,” said Druckenmiller, who has studied dinosaurs in the region for more than a decade. “With every new species, we paint a new picture of this ancient polar landscape.”
Marsupials are a type of mammal that carries underdeveloped offspring in a pouch. Kangaroos and koalas are the best-known modern marsupials. Ancient relatives were much smaller during the late Cretaceous, Druckenmiller said. Unnuakomys hutchisoniwas probably more like a tiny opossum, feeding on insects and plants while surviving in darkness for as many as four months each winter.
The research team, whose project was funded with a National Science Foundation grant, identified the new marsupial using a painstaking process. With the help of numerous graduate and undergraduate students, they collected, washed and screened ancient river sediment collected on the North Slope and then carefully inspected it under a microscope. Over many years, they were able to locate numerous fossilized teeth roughly the size of a grain of sand.
“I liken it to searching for proverbial needles in haystacks — more rocks than fossils,” said Florida State University paleobiologist Gregory Erickson, who contributed to the paper.
Jaelyn Eberle, curator of fossil vertebrates at the University of Colorado Museum of Natural History, led the effort to examine those teeth and a few tiny jawbones. Their analysis revealed a new species and genus of marsupial.
Mammal teeth have unique cusps that differ from species to species, making them a bit like fingerprints for long-dead organisms, said Eberle, the lead author of the study.
“If I were to go down to the Denver Zoo and crank open the mouth of a lion and look in — which I don’t recommend — I could tell you its genus and probably its species based only on its cheek teeth,” Eberle said.
The name Unnuakomys hutchisoni combines the Iñupiaq word for “night” and the Greek word “mys” for mouse, a reference to the dark winters the animal endured, and a tribute to J. Howard Hutchison, a paleontologist who discovered the fossil-rich site where its teeth were eventually found.
Other co-authors of the Journal of Systematic Palaeontology paper include William Clemens, of the University of California, Berkeley; Paul McCarthy, of UAF; and Anthony Fiorillo, of the Perot Museum of Nature and Science.
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Neanderthal footprints found in Gibraltar
The international journal Quaternary Science Reviews has just published a paper which has involved the participation of Gibraltarian scientists from The Gibraltar National Museum alongside colleagues from Spain, Portugal and Japan. The results which have been published come from an area of the Catalan Bay Sand Dune.
This work started ten years ago, when the first dates using the OSL method were obtained. It is then that the first traces of footprints left by vertebrates were found. In subsequent years the successive natural collapse of sand has revealed further material and has permitted a detailed study including new dates.
The sand sheets in the rampant dunes above Catalan Bay are a relic of the last glaciation, when sea level was up to 120 metres below present levels and a great field of dunes extended eastwards from the base of the Rock. The identified footprints correspond to species which are known, from fossil material, to have inhabited Gibraltar. The identified footprints correspond to Red Deer, Ibex, Aurochs, Leopard and Straight-tusked Elephant. In addition the scientists have found the footprint of a young human (106-126 cm in height), possibly Neanderthal, which dates to around 29 thousand years ago. It would coincide with late Neanderthal dates from Gorham’s Cave.
If confirmed to be Neanderthal, these dunes would become only the second site in the world with footprints attributed to these humans, the other being Vartop Cave in Romania. These findings add further international importance to the Gibraltar Pleistocene heritage, declared of World Heritage Value in 2016.
The research was supported by HM Government of Gibraltar under the Gibraltar Caves Project and the annual excavations in the Gibraltar Caves, with additional support to the external scientists from the Spanish EU project MICINN-FEDER: CGL2010-15810/BTE.
Minister for Heritage John Cortes MP commented, “This is extraordinary research and gives us an incredible insight into the wildlife community of Gibraltar’s past. We should all take a moment to imagine the scene when these animals walked across our landscape. It helps us understand the importance of looking after our heritage. I congratulate the research team on uncovering this fascinating, hidden evidence of our Rock’s past.”
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New dinosaur with heart-shaped tail provides evolutionary clues for African continent
A new dinosaur that wears its “heart” on its tail provides new clues to how ecosystems evolved on the African continent during the Cretaceous period according to researchers at Ohio University.
The OHIO team identified and named the new species of dinosaur in an article published this week in PLOS ONE. The new dinosaur, the third now described from southwestern Tanzania by the NSF-funded team, is yet another member of the large, long-necked titanosaur sauropods. The partial skeleton was recovered from Cretaceous-age (~100 million years ago) rocks exposed in a cliff surface in the western branch of the great East African Rift System.
The new dinosaur is named Mnyamawamtuka moyowamkia (Mm-nya-ma-wah-mm-too-ka mm-oh-yo-wa-mm-key-ah), a name derived from Swahili for “animal of the Mtuka (with) a heart-shaped tail” in reference to the name of the riverbed (Mtuka) in which it was discovered and due to the unique shape of its tail bones.
The initial discovery of Mnyamawamtuka took place in 2004, when part of the skeleton was discovered high in a cliff wall overlooking the seasonally dry Mtuka riverbed, with annual excavations continuing through 2008. “Although titanosaurs became one of the most successful dinosaur groups before the infamous mass extinction capping the Age of Dinosaurs, their early evolutionary history remains obscure, and Mnyamawamtuka helps tell those beginnings, especially for their African-side of the story,” said lead author Dr. Eric Gorscak, a recent Ph.D. graduate of Ohio University, current research associate at the Field Museum of Natural History (Chicago) and new assistant professor at the Midwestern University in Downers Grove, just outside of Chicago. “The wealth of information from the skeleton indicates it was distantly related to other known African titanosaurs, except for some interesting similarities with another dinosaur, Malawisaurus, from just across the Tanzania-Malawi border,” noted Dr. Gorscak.
Titanosaurs are best known from Cretaceous-age rocks in South America, but other efforts by the team include new species discovered in Tanzania, Egypt, and other parts of the African continent that reveal a more complex picture of dinosaurian evolution on the planet. “The discovery of dinosaurs like Mnyamawamtuka and others we have recently discovered is like doing a four-dimensional connect the dots,” said Dr. Patrick O’Connor, professor of anatomy at Ohio University and Gorscak’s advisor during his Ph.D. research. “Each new discovery adds a bit more detail to the picture of what ecosystems on continental Africa were like during the Cretaceous, allowing us to assemble a more holistic view of biotic change in the past.”
The excavation process spanned multiple years, and included field teams suspended by ropes and large-scale mechanical excavators to recover one of the more complete specimens from this part of the sauropod dinosaur family tree. “Without the dedication of several field teams, including some whose members donned climbing gear for the early excavations, the skeleton would have eroded away into the river during quite intense wet seasons in this part of the East African Rift System,” added O’Connor.
“This latest discovery is yet another fine example of how Ohio University researchers work the world over in their pursuit of scientific research,” Ohio University President M. Duane Nellis said. “This team has turned out a number of notable discoveries which collectively contribute significantly to our understanding of the natural world.”
Mnyamawamtuka and the other Tanzanian titanosaurs are not the only animals discovered by the research team. Remains of bizarre relatives of early crocodiles, the oldest evidence for “insect farming,” and tantalizing clues about the early evolution of monkeys and apes have been discovered in recent years. Such findings from the East African Rift provide a crucial glimpse into ancient ecosystems of Africa and provide the impetus for future work elsewhere on the continent.
“This new dinosaur gives us important information about African fauna during a time of evolutionary change,” said Judy Skog, a program director in the National Science Foundation’s Division of Earth Sciences, which funded the research. “The discovery offers insights into paleogeography during the Cretaceous. It’s also timely information about an animal with heart-shaped tail bones during this week of Valentine’s Day.”
Recent findings by the research team in the Rukwa Rift Basin include:
“The Tanzanian story is far from over but we know enough to start asking what paleontological and geological similarities and dissimilarities there are with nearby rock units. Revisiting Malawi is my top priority to address these broader, regional questions,” said Gorscak, who also participates in ongoing projects in Egypt and Kenya. “With Mnyamawamtuka and other discoveries, I’m not sure to view it as writing or reading the next chapters in the paleontological book of Africa. I’m just excited to see where this story is going to take us.”
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Science Newsfrom research organizations Earliest known seed-eating perching bird discovered in Fossil Lake, Wyoming
Most of the birds you’ve ever seen — sparrows, finches, robins, crows — have one crucial thing in common: they’re all what scientists refer to as perching birds, or “passerines.” The passerines make up about 6,500 of the 10,000 bird species alive today. But while they’re everywhere now, they were once rare, and scientists are still learning about their origins. In a new paper in Current Biology, researchers have announced the discovery of one of the earliest known passerine birds, from 52 million years ago.
“This is one of the earliest known perching birds. It’s fascinating because passerines today make up most of all bird species, but they were extremely rare back then. This particular piece is just exquisite,” says Field Museum Neguanee Distinguished Service Curator Lance Grande, an author of the paper. “It is a complete skeleton with the feathers still attached, which is extremely rare in the fossil record of birds.”
The paper describes two new fossil bird species — one from Germany that lived 47 million years ago, and another that lived in what’s now Wyoming 52 million years ago, a period known as the Early Eocene. The Wyoming bird, Eofringillirostrum boudreauxi, is the earliest example of a bird with a finch-like beak, similar to today’s sparrows and finches. This legacy is reflected in its name; Eofringilllirostrum means “dawn finch beak.” (Meanwhile, boudreauxi is a nod to Terry and Gail Boudreaux, longtime supporters of science at the Field Museum.)”
The fossil birds’ finch-like, thick beaks hint at their diet. “These bills are particularly well-suited for consuming small, hard seeds,” says Daniel Ksepka, the paper’s lead author, curator at the Bruce Museum in Connecticut. Anyone with a birdfeeder knows that lots of birds are nuts for seeds, but seed-eating is a fairly recent biological phenomenon. “The earliest birds probably ate insects and fish, some may have been eating small lizards,” says Grande. “Until this discovery, we did not know much about the ecology of early passerines. E. boudreauxi gives us an important look at this.”
“We were able to show that a comparable diversity of bill types already developed in the Eocene in very early ancestors of passerines,” says co-author Gerald Mayr of the Senckenberg Research Institute in Frankfurt. “The great distance between the two fossil sites implies that these birds were widespread during the Eocene, while the scarcity of known fossils suggests a rather low number of individuals,” adds Ksepka.
While passerine birds were rare 52 million years ago, E. boudreauxi had the good luck to live and die near Fossil Lake, a site famous for perfect fossilization conditions.
“Fossil Lake is a really graphic picture of an entire community locked in stone — it has everything from fishes and crocs to insects, pollen, reptiles, birds, and early mammals,” says Grande. “We have spent so much time excavating this locality, that we have a record of even the very rare things.”
Grande notes that Fossil Lake provides a unique look at the ancient world — one of the most detailed pictures of life on Earth after the extinction of the dinosaurs (minus the birds) 65 million years ago. “Knowing what happened in the past gives us a better understanding of the present and may help us figure out where we are going for the future.”
With that in mind, Grande plans to continue his exploration of the locale. “I’ve been going to Fossil Lake every year for the last 35 years, and finding this bird is one of the reasons I keep going back. It’s so rich,” says Grande. “We keep finding things that no one’s ever seen before.”
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