December 30 , 2016:

by Vasika Udurawane

This is a list of the most scientifically influential fossil stories of 2016. Not only do we have new species turning up at a breakneck pace, like a “three-eyed” Triassic reptile and an invertebrate that carried its young like kites, but we have also gained a new perspective of how life on Earth even began with the oldest fossil remains of all time.

She's got Dollocaris eyes

Image credit: Andrey Atuchin
Location: Europe
Age: Jurassic Period

The odd Mid-Jurassic crustacean relative Dollocaris ingens resembles a creature straight out of science fiction. The creature was 20 centimeters long and had a prawn-like body and limbs for swimming, as well as set of pincers for grasping its small floating prey.

However Dollocaris’s strangest feature was its eyes. Each eye had 18,000 lenses and were a quarter of its body length. They were used by this poor swimmer to locate the other invertebrates and small fish that it ate. Dollocaris isn't a new discovery, but its huge eyes were once thought to be ‘cephalic sacs’ or a stomach-type organ. Recent research by researcher Jean Vannier from the University of Lyon in France has revealed the truth about the animal and its bizarre eyes.

Despite looking like a proper crustacean, the creature was only distantly related, belonging to a family known as the thylacocephalans. These marine invertebrates lasted roughly 400 million years, going extinct only when the Age of Dinosaurs ended. Dollocaris comes from France’s La Voulte-sur-Rhone and is about 163 million years old, Mid Jurassic in age. It was found among a slew of other small animals like prawns and shrimp, crabs, octopuses, squid and small fish.

The original child leash

Image credit: Andrey Atuchin
Location: Europe
Age: Silurian Period

Nicknamed the “Kite Runner” after Khaled Hosseini’s bestselling novel, the little invertebrate Aquilonifer spinosus had a unique way of protecting and transporting its young. Found in the 430-million-year-old Herefordshire Beds of the English Midlands, this creature was found with its ten offspring in tow, kept tethered to its body by a series of long organic threads.

The mother Aquilonifer was tiny, at a mere centimeter long and it had a pair of huge, spiny feelers as well as a series of swimming legs like a larval crab. Her young were found to be in three stages of development, thus suggesting a much better mother than most invertebrates.

Image credit: Allen Nutman
Location: North America
Age: Archean Eon

Stromatolites may not look very exciting at first glance. Their layers look something like puff pastry made of stone, and are actually structures created through the activity of microbial organisms, mainly cyanobacteria. These collections of microbial mats are some of the most ancient fossils in the world, previously recorded at 3.5 billion years old. Now however, a new stromatolite colony from some of Greenland’s most ancient rocks has been revealed.

This new colony consists of conical stromatolite structures roughly four centimeters long and a centimeter tall, much smaller than the popular Australian Shark Bay colony which is still forming today. The team behind the discovery cannot yet identify exactly what microbes that formed these colonies. What they do know is that these stromatolites were formed by a process similar to those at Shark Bay: Microbial mats would trap bits of sediment over time and keep building up until they formed a small colony and finally a unified structure.

These fossils point to 3.7-billion-year stromatolite colonies and a complete revamping in our understanding of the Earth’s earliest days as a planet covered by newly formed global oceans rather than a hot, molten mass bombarded by asteroids.

Image credit: Julio Lacerda
Location: North America
Age: Triassic Period

This is yet another strange beast from the Triassic, although its oddness is a little less obvious at first glance. Named Triopticus primus, it had bony knobs and protrusions surrounding a dome-like skull with a deep pit resembling a third eye.

It was a very distant cousin of both dinosaurs and crocodiles. Its domed skull was also markedly similar to a very different group of animals that would appear many millions of years later during the Cretaceous: the bonehead dinosaurs. Called the pachycephalosaurids, these dinosaurs are known for having very thickened dome-like skulls possibly used in headbutting contests between rivals.

Triopticus also had a deep pit in its skull, something that the dinosaurs lacked completely. The primary idea Michelle Stocker and colleagues suggested that it was simply a part of the skull roof that never became thickened while everything around it did, forming a pit. A secondary hypothesis was that it was a hole for a pineal eye which fed light to the pineal gland in the brain, a so-called "third eye." Even the name of the animal alludes to this, with Triopticus primus translated as “first three-eyed one."

Image credit: Photograph by Jakob Vinter, University of Bristol and Bob Nicholls
Location: Asia
Age: Cretaceous Period

Conventional wisdom once told us that it would be impossible to glean the exact colors of dinosaurs from their fossil bones. Recently though, reexamination of a small herbivorous dinosaur has revealed exactly that. A team led by Jakob Vinther examined a specimen of Psittacosaurus from the Yixian Formation of China’s Jehol region. Psittacosaurus is an early cousin of the giant horned dinosaurs, but it was much smaller, walked on two legs, only had cheek horns, and a parrot-like beak.

The team examined the specimen under an electron microscope and found traces of the animal’s pigment-producing organelles, known as melanosomes. This allowed the paleontologists to determine the exact color patterns that it had in life. Vinther and his team had already revealed the colors of several feathered dinosaurs close to the evolution of birds, uncovering the preserved melanosomes from within the feathers.

Psittacosaurus had scaly skin covering almost its entire body, and the coloration of a primarily scaly dinosaur had never been revealed until now. In life it had a kind of coloration called countershading, a camouflage technique that many modern-day herbivorous mammals in its size range often employ. The animal’s upper parts were dark brown and black than those pinkish brown.

Psittacosaurus' two-toned coloration helped to flatten out its outline when seen in partial light. This would make the Psittacosaurus harder to detect in its closed forest habitat, a valuable strategy for a dinosaur barely two meters in length. There were some variation in its colors, having a much darker head and some small blotches of pigment on its shoulders. Vinther and team were also able to reveal that Psittacosaurus had a pair of very large eyes, effective for finding food under low light conditions.

Image credit: Jamie Hiscocks
Location: Europe
Age: Cretaceous Period

While dinosaur braincases or endocasts might be important in the fossil record, actual mineralized brain tissue is the next best thing. This exciting find, from a beach in Bexhill in Sussex consists of the braincase of an Iguanodon-like herbivore that lived around 133 million years ago. The tantalizing fossil find was first uncovered in 2004 but only in 2016 was it officially announced at the Society of Vertebrate Paleontology’s annual meeting in Salt Lake City.

Well-known Iguanodon expert Dr David Norman and colleagues revealed that the animal might have been at least on par with a crocodile in terms of intelligence even though this is hard to gauge accurately. There is not much of the brain tissue preserved, merely a small section of the animal’s meninges, the part that protects and nourishes the brain and a section of the cortex or the brain’s outer layer.

All in all, whatever is left of the brain is rather similar to those of today’s birds and crocodilians. The structure of the meningeal blood vessels has been preserved against the fossil skull. It was theorized by Norman and colleagues that the dinosaur sank to the bottom of a stagnant pond, and that the acidity of the water helped to preserve the animal’s brain tissues in such a unique manner.

It is thought that while the water ate away at much of the body and blood of the dinosaur, this process of corrosion released charged atoms that helped to mineralize and fossilize the soft tissue of the animal’s brain. While dinosaur mummies of all description have been found, none of these have displayed the level of incredible preservation that the British find shows.

Prehistoric turducken

Image credit: Springer Heidelberg and Krister Smith
Location: Europe
Age: Eocene Epoch

Forty-eight million years ago, in the Early Eocene of Germany, a lizard ate up a small insect, only for an ancient snake to grab and swallow it whole. Said snake then slipped, perhaps unwittingly, into one of the volcanic lakes in its tropical forest environment and died with its meal still inside. This fossil was discovered in the famous Messel Shale of Germany and published in the journal Paleobiodiversity and Paleoenvironments.

While the insect was not identifiable, the lizard was properly identified as the ancestral basilisk Geiseltaliellus maarius and was a tree-dweller that as an adult, fed on plants. This makes it similar in behavior and dietary preferences to a modern basilisk lizard.

The snake, also a tree-dweller, was identified as a juvenile of the already well-known Messel constrictor Palaeopython fischeri. It was a rather small boa that often reached two meters in length. It had swallowed the juvenile lizard whole, and thus allowed for the preservation of three levels of a Messel food chain.

Many fossils from this site are preserved in exquisite detail due to the presence of volcanism in the region, thus allowing for intricacies like those in the so-called Eocene “turducken”.

Image credit: Julio Lacerda
Location: North America
Age: Pennsylvanian Epoch of the Carboniferous Period

The soft-bodied Tullimonstrum gregarium has confounded scientists since its discovery in 1966 in Carboniferous sediments from Mazon Creek at Illinois. It had a body like a cuttlefish, complete with a little pair of fins, a lengthy proboscis with jaws at the end and eyes mounted on stalks.

The animal was sometimes classified as a swimming mollusk and sometimes as a creature unrelated to any other animal group alive today. However its real identity has now been revealed. Tullimonstrum – the “Tully Monster” for short – was not an invertebrate but rather an ancient fish related to modern jawless fish like lampreys and hagfishes.

Not only did it have a set of teeth in its jaws but X-ray analysis of the fossils showed that it had gills and a stiffened rod down its back or notochord. Even the pigmentation in the animal’s eyes was discovered, thus prompting a completely revamped reconstruction of the animal. Its fins were arranged vertically, like that of a fish’s tail and it held its jaw-tipped proboscis straight in front of its body to snap at any tiny prey items that floated by.

Image credit: Joschua Knüppe
Location: Asia
Age: Triassic Period

One of the strangest animals to come out of the Triassic was the marine reptile Atopodentatus unicus. While the animal was originally found in China’s Luoping Province in 2014, it took a while for scientists to determine exactly what it looked like and how it behaved.

The original find had a crushed skull, and this prompted a very strange and somewhat nightmarish reconstruction of Atopodentatus. The jaws were given a zipper-like opening, with the animal portrayed as dragging its head through the sand to filter out small invertebrates, an animal unlike anything alive today.

New remains show that the three-meter reptile was a bottom feeder that vacuumed up algae with somewhat hammerhead-like jaws. In a sea full of fish-eaters, this was one of the earliest marine reptiles to adapt to a herbivorous lifestyle. This results in a creature that looks somehow more conventional and downright normal in comparison to earlier restorations.

Image credit: Yu Chen/PA
Location: Asia
Age: Jurassic Period

Some adult and juvenile dinosaurs looked remarkably different, going through several growth morphs before reaching skeletal maturity. However, one dinosaur managed to defy expectations altogether by losing its teeth completely as it entered adulthood, something never before seen in dinosaurs.

This decidedly odd beast is Limusaurus inextricabilis and it hails from 160-million-year old rocks in China’s Wucaiwan. It is a ceratosaur, related to the famously dragon-like horned predator Ceratosaurus from the Late Jurassic of North America. Fossils of the adult Limusaurus showed that it was a small and graceful 1.5-meter animal with a tiny head, long neck and legs and very short arms.

It also lacked teeth and was possibly a fast-running low-level vegetarian. Researchers from the George Washington University examined about 19 specimens of the animal, found in various “predator traps” created when volcanic ash fell and got mixed in with mud from the neighboring marshes. These traps revealed not just adults a decade old but also the bones of very young Limusaurus which showed the extreme growth of the animal.

The youngsters had short skulls and a full set of 42 teeth in their jaws, perfect for ripping into hard-shelled insects and other small animals. They were mature at around six years old, and by the time they were adults they had lost their teeth completely.

Adult Limusaurus were found in association with gastroliths, so-called stomach stones that they swallowed to help grind up their food like many herbivorous birds do today. Even the head shapes altered quite a bit, becoming shallower and smaller in comparison to the bodies as the little dinosaurs aged.

Image credit: Joschua Knüppe
Location: Asia
Age: Cretaceous Period

One more surprise to come out of Burmese amber nuggets was the so-called “unicorn ant” Ceratomyrmex ellenbergei. The find was published by a team comprising Vincent Perrichot, Wang Bo and Michael Engel in the scientific journal Current Biology. Altogether, four specimens were discovered, with the holotype, or reference specimen, being that of a worker ant. Among all the little oddities in the Hukawng Valley, this ant has to be among the weirdest yet due to the strange orientation of its jaws. They resembled a pair of upturned scythe blades, used for grabbing struggling prey.

Ceratomyrmex gets its common name of "unicorn ant" from the prominent horn on its head. The horn was also crowned in hairs known as setae, which the authors of the paper theorize helped to comfortably transport the larvae and pupae. Alternatively the ant’s huge horn may have helped in prey capture, with the setae working as hair triggers to close upon its unsuspecting victims.

Image credit: Nicole Fuller/Sayo Art for UT Austin
Location: Antarctica
Age: Cretaceous Period

Bird calls are created through a rather specialized organ, a voice box known as a syrinx. This structure is also composed of cartilaginous folds and loops, but is located in the chest cavity rather than in the throat like a larynx. This discovery of the oldest fossilized syrinx shows us that the evolution of this organ happened relatively late in the history of birds.

There are no fossilized syrinxes that are older and they thus only developed with the appearance of anatomically modern birds. Vegavis iaai was an ancient species of waterfowl, a very old evolutionary cousin of modern geese and ducks that lived close to the end of the dinosaur era. Fossils of this bird hail from Vega Island in Antarctica and probably produced honking calls just like a goose today.

Dinosaur tail and bird wing in amber

Image credit: Ryan C. McKellar
Location: Asia
Age: Cretaceous Period

The 99-million-year-old amber deposits of Myanmar’s Hukawng Valley in the province of Kachin, have helped to reconstruct an entire Cretaceous ecosystem from the ground up. Trapped in the fossilized resin are the remains of ancestral geckos and chameleons, predatory cockroaches, giant termites and some decidedly weird-looking ants.

This year though, another find was revealed, coming from something much larger than an insect. It was the discovery of a portion of dinosaur tail, with not just eight vertebrae but even some of the tail feathers and soft tissues all intact. The feathers were found to have been soft and fluffy rather than sleek and aerodynamic.

It was also a very young, sparrow-sized animal in real life and is currently thought to have been a close relative of the carnivorous raptor dinosaurs. The amber specimen was published by Lida Xing in the journal Current Biology and was one of twelve other specimens destined for the jewelry industry.

Another rather spectacular amber find from the same region and also mined for a pendant, was that of a pair of proper bird wings stuck in tree resin. These specimens were published in a paper authored once again by Xing and published in the journal Nature Communications. According to Xing and Ryan McKellar from Canada’s Royal Saskatchewan Museum, the bird belonged to a now-extinct family called the enantiornithines or “opposite birds”.

These birds, still retaining tiny claws on their wings, were very common during the Age of Dinosaurs, spreading through the world and existing in a variety of habitats. They lacked fans of stiffened tail feathers, instead bearing a pair of ribbon-like feathers or nothing at all.

This particular bird may have been the size of a hummingbird and was, like the feathered dinosaur, a very young animal. The find shows us that these ancient birds could look after themselves straight after hatching, just like baby ostriches can.