Fossils of earliest stick insect to mimic plants discovered: Ancient stick insect species mimicked plant leaves

An ancient stick insect species may have mimicked plant leaves for defense, according to a paper published in the open-access journalPLOS ONE on March 19, 2014 by Maomin Wang, from Capital Normal University, China and colleagues.

Many insects have developed defense mechanisms, including the ability to mimic the surrounding environment. Stick and leaf insects mimic plants from their environment, but scientists know little about the original of this interaction due to little or no previous stick insect fossil records showing this adaptation. The scientists discovered three specimens, one female and two males, belonging to a new fossil stick insect referred to as Cretophasmomima melanogramma, in Inner Mongolia at the Jehol locality, a site from the Cretaceous period (approximately 126 million years ago). The species possessed adaptive features that make it resembling a plant recovered from the same locality.

The insects’ wings have parallel dark lines and when in the resting position, likely produced a tongue-like shape concealing the abdomen. Fossils from a relative of the ginkgo plant have been documented in the area with similar tongue-shaped leaves along with multiple longitudinal lines. The authors suggest the insect used this plant as a model for concealment.

The new fossils indicate that leaf mimicry was a defensive strategy performed by some insects as early as in the Early Cretaceous, but that additional refinements characteristic of recent forms, such as a curved part of the fore legs for hiding the head, were still lacking.

The new fossil suggests that leaf mimicry predated the appearance of twig and bark mimicry in these types of insects. The diversification of small-sized, insect-eating birds and mammals may have triggered the acquisition of such primary defenses.


Nearly complete ‘chicken from hell,’ from mysterious dinosaur group

A Team of researchers has announced the discovery of a bizarre, bird-like dinosaur, named Anzu wyliei, that provides paleontologists with their first good look at a dinosaur group that has been shrouded in mystery for almost a century. Anzu was described from three specimens that collectively preserve almost the entire skeleton, giving scientists a remarkable opportunity to study the anatomy and evolutionary relationships of Caenagnathidae (pronounced SEE-nuh-NAY-thih-DAY) — the long-mysterious group of theropod dinosaurs to which Anzu belongs.

The three described fossil skeletons of Anzu were unearthed in North and South Dakota, from roughly 66 million-year-old rocks of the Hell Creek Formation, a rock unit celebrated for its abundant fossils of famous dinosaurs such as Tyrannosaurus rex and Triceratops. The scientific paper describing the discovery appears today in the freely-accessible journal PLOS ONE.

The team of scientists who studied Anzu was led by Dr. Matthew Lamanna of Carnegie Museum of Natural History in Pittsburgh. Dr. Lamanna’s collaborators include Dr. Hans-Dieter Sues and Dr. Tyler Lyson of the Smithsonian Institution’s National Museum of Natural History in Washington, DC, and Dr. Emma Schachner of the University of Utah in Salt Lake City. According to Dr. Lamanna, “Anzu is far and away the most complete caenagnathid that has ever been discovered. After nearly a century of searching, we paleontologists finally have the fossils to show what these creatures looked like from virtually head to toe. And in almost every way, they’re even weirder than we imagined.”

Hell’s Chicken

At roughly 11 feet long and five feet tall at the hip, Anzu would have resembled a gigantic flightless bird, more than a ‘typical’ theropod dinosaur such as T. rex. Its jaws were tipped with a toothless beak, and its head sported a tall, rounded crest similar to that of a cassowary (a large ground bird native to Australia and New Guinea). The neck and hind legs were long and slender, also comparable to a cassowary or ostrich. Although the Anzu specimens preserve only bones, close relatives of this dinosaur have been found with fossilized feathers, strongly suggesting that the new creature was feathered too. The resemblance to birds ends there, however: the forelimbs ofAnzu were tipped with large, sharp claws, and the tail was long and robust. Says Dr. Lamanna, “We jokingly call this thing the ‘Chicken from Hell,’ and I think that’s pretty appropriate. So we named it after Anzu, a bird-like demon in ancient mythology.”

The species is named for a Carnegie Museums of Pittsburgh Trustee’s grandson, Wylie.

Not only do the fossils of Anzu wyliei paint a picture of this particular species, they shed light on an entire group of dinosaurs, the first evidence of which was discovered almost 100 years ago. In 1924, paleontologist Charles Whitney Gilmore described the species Chirostenotes pergracilis from a pair of fossil hands found a decade earlier in ~74 million-year-old rocks in Alberta, Canada. Later, in 1940, Caenagnathus collinsiwas named, based on a peculiar lower jaw from the same beds. More recently, after studies of these and other fragmentary fossils, Hans Sues and other paleontologists determined that Chirostenotes and Caenagnathus belonged to the same dinosaur group, Caenagnathidae, and that these animals were close cousins of Asian oviraptorid theropods such as Oviraptor.

Asian relations

Oviraptor (‘egg thief’) is widely known because the first fossil skeleton of this animal, described in 1924, was found atop a nest of dinosaur eggs, suggesting that the creature had died in the act of raiding the nest. This thinking prevailed until the 1990s, when the same type of egg was found with a baby oviraptorid inside, demonstrating that, rather than a nest plunderer, Oviraptor was a caring parent that perished while protecting its eggs. More than a dozen oviraptorid species have been discovered, all in Mongolia and China, and many are known from beautifully-preserved, complete or nearly complete skeletons. Additionally, beginning in the 1990s, several small, primitive relatives of oviraptorids were unearthed in much older, ~125 million-year-old rocks in northeastern China. Many of these are also represented by complete skulls or skeletons, some of which preserve fossilized feathers. Researchers have established that caenagnathids, oviraptorids, and these more archaic Chinese species are closely related to one another, and have united them as the theropod group Oviraptorosauria. The occurrence of oviraptorosaurs in both Asia and North America was not a surprise to paleontologists, because these continents were frequently connected during the Mesozoic Era (the ‘Age of Dinosaurs’), allowing dinosaurs and other land animals to roam between them. However, because their fossils were so incomplete, caenagnathids remained the most poorly known members of Oviraptorosauria, and indeed, one of the least understood of all major dinosaur groups. “For many years, caenagnathids were known only from a few bits of the skeleton, and their appearance remained a big mystery,” says Dr. Sues.

More fossils, more knowledge

The nearly completely represented skeleton of Anzu opens a window into the anatomy of this and other caenagnathid species. Armed with this wealth of new information, Dr. Lamanna and his team were able to reconstruct the evolution of these extraordinary animals in more detail than ever before. Analysis of the relationships of Anzureaffirmed that caenagnathids form a natural grouping within Oviraptorosauria: Anzu,CaenagnathusChirostenotes, and other North American oviraptorosaurs are more closely related to each other than they are to most of their Asian cousins — a finding that had been disputed in recent years. Furthermore, the team’s analysis confirmed the recent hypothesis that the enormous (and aptly-named) Gigantoraptor — at a weight of at least 1.5 tons, the largest oviraptorosaur known to science — is an unusual member of Caenagnathidae as well, instead of an oviraptorid as had initially been proposed. “We’re finding that caenagnathids were an amazingly diverse bunch of dinosaurs,” says Dr. Lamanna. “Whereas some were turkey-sized, others — like Anzuand Gigantoraptor — were the kind of thing you definitely wouldn’t want to meet in a dark alley. Apparently these oviraptorosaurs occupied a much wider range of body sizes and ecologies than we previously thought.”

The anatomy and ancient environment of Anzu provide insight into the diet and habitat preferences of caenagnathids as well. Although the preferred food of these oviraptorosaurs remains something of a puzzle, Dr. Lamanna and collaborators think that caenagnathids were probably omnivores — like humans, animals that could eat either meat or plants. Moreover, studies of the rocks in which several of the most complete caenagnathid skeletons have been found show that these strata were laid down in humid floodplain environments, suggesting that these dinosaurs favored such habitats. In this way, caenagnathids appear to have differed greatly from their oviraptorid cousins, all of which have been found in rocks that were deposited under arid to semi-arid conditions . “Over the years, we’ve noticed that Anzu and some other Hell Creek Formation dinosaurs, such as Triceratops, are often found in mudstone rock that was deposited on ancient floodplains. Other dinosaurs, like duckbills, are found in sandstone deposited in or next to rivers,” says Dr. Lyson, who found his first Hell Creek fossil on his family’s ranch in North Dakota when he was only six years old.

Anzu led a life that was fraught with danger. In addition to sharing its Cretaceous world with the most notorious carnivore of all time — T. rex — this oviraptorosaur seems to have gotten hurt a lot as well. Two of the three specimens show clear evidence of injuries: one has a broken and healed rib, while the other has an arthritic toe bone that may have been caused by an avulsion fracture (where a tendon ripped a piece off the bone to which it was attached). Says Dr. Schachner, “These animals were clearly able to survive quite a bit of trauma, as two of the specimens show signs of semi-healed damage. Whether these injuries were the result of combat between two individuals or an attack by a larger predator remains a mystery.”

As much insight as the Anzu skeletons provide, paleontologists still have much to learn about North American oviraptorosaurs. Ongoing studies of these and other important fossils promise to remove more of the mystery surrounding these remarkable bird-like creatures. “For nearly a hundred years, we paleontologists knew almost nothing about these dinosaurs,” concludes Dr. Lamanna. “Now, thanks to Anzu, we’re finally starting to figure them out.”

A fully-articulated cast of Anzu wyliei is on public view in Carnegie Museum of Natural History’s Dinosaurs in Their Time exhibition.

Bighead carp: From 5 to 150 centimeters in 37 million years

During excavations in the open lignite-mining pit Na Duong in Vietnam, a joint team from the University of Tübingen and the Senckenberg Center for Human Evolution and Palaeoenvironment Tübingen discovered the world’s oldest bighead carp. With a length of only 5 centimeters, Planktophaga minuta is also the smallest known fossil representative of this East Asian group. Modern bighead carp are among the largest members of the carp family, reaching a length of up to 1.5 meters and a weight of 50 kilograms.

Since 2008, an international research team led by Prof. Dr. Madelaine Böhme from the Senckenberg Center for Human Evolution and Palaeoenvironment (HEP) of the University of Tübingen has been studying prehistoric ecosystems and fossils in Vietnam. In the course of this research the scientists discovered approximately 37 million-year-old sediments from Lake RhinChua, dating to the late Eocene. These freshwater sediments contained a wealth of fossilized animals and plants; hence, Lake RhinChua is also referred to as the “Asian Messel” by the researchers.

During their studies the team discovered teeth belonging to an entirely new genus and species of fish: The oldest known bighead carp, Planktophaga minuta, is a representative of the “East Asian group of Leuciscinae.” With a length of ca. 5 centimeters it is the smallest fossil representative of this East Asian group, and a mere dwarf compared to its modern living relatives. Modern bighead carp are among the largest members of the carp family. They grow up to a length of 1.5 meters and can weigh in at 50 kilograms.

Planktophaga minuta and its relatives

Besides Planktophaga minuta (which translates to small plankton eater), an additional six species of carp have been discovered in Lake RhinChua. All of them have living relatives that are still found today in China’s Pearl and Yangtze River system. This is proof that the roots of the modern freshwater fish fauna in Southeast Asia reach far into the past.

Bighead carp in exile

Originally, the bighead carp was native to the larger rivers and stagnant water bodies of southern China. During the 1960s, bighead carp were introduced in Europe, including Germany, as a means to control aquatic plants. Only later did researchers discover that the bighead carp failed to “fulfill this task,” since they mainly feed on animal plankton. In Europe, introduced bighead carp can be found in ponds, lakes and occasionally in streams and rivers.

Dinosaur skull may reveal T. rex’s smaller cousin from the north

A 70 million year old fossil found in the Late Cretaceous sediments of Alaska reveals a new small tyrannosaur, according to a paper published in the open-access journal PLOS ONE on March 12, 2014 by co-authors Anthony Fiorillo and Ronald S. Tykoski from Perot Museum of Nature and Science, Texas, and colleagues.

Tyrannosaurs, the lineage of carnivorous theropod (“beast feet”) dinosaurs that include T. rex, have captivated our attention, but the majority of our knowledge about this group comes from fossils from low- to mid-latitudes of North America and Asia. In this study, scientists analyzed the partial skull roof, maxilla, and jaw, recovered from Prince Creek Formation in Northern Alaska, of a dinosaur originally believed to belong to a different species, and then compared the fossils to known tyrannosaurine species.

According to the results of the authors’ analysis, the cranial bones represent Nanuqsaurus hoglundi, a new tyrannosaurine species closely related to two other tyrannosaurides, Tarbosaurus and Tyrannosaurus. This new dinosaur is estimated to be relatively small, with an adult skull length estimated at 25 inches, compared to 60 inches for T. rex. The new species likely inhabited a seasonally extreme, high-latitude continental environment on the northernmost edge of Cretaceous North America.

The authors suggest that the smaller body size of N. hoglundi compared to most tyrannosaurids from lower latitudes may reflect an adaptation to variability in resources in the arctic seasons. Further diversification may stem from the dinosaurs’ partial isolation in the north by land barriers, such as the east-west running Brooks Range. Although the preserved elements of N. hoglundi are fragments, the authors point to morphological data to provide support for its place among derived tyrannosaurines. This discovery may provide new insights into the adaptability and evolution of tyrannosaurs in a different environment, the Arctic.

“The ‘pygmy tyrannosaur’ alone is really cool because it tells us something about what the environment was like in the ancient Arctic,” said Fiorillo. “But what makes this discovery even more exciting is that Nanuqsaurus hoglundi also tells us about the biological richness of the ancient polar world during a time when the Earth was very warm compared to today.”