Shoo, Shoo Shuvuuia: Nocturnal Owl-Like Dinosaur with Keen Eyesight and Acute Hearing

            A small  carnivorous dinosaur had superb low-light vision and hearing that was likely as good as an owl's. And like an owl, the tiny dinosaur probably used those exceptional abilities to stalk and catch its desert prey under the cover of darkness.

    The owl-like Shuvuuia (shu-VU-ya) was a theropod, a three-toed and bipedal carnivorous dinosaur. There's only one known species, Shuvuuia deserti, and it was smaller than a domestic cat, measuring 2 feet (0.6 meters) long. Shuvuuia lived about 75 million to 81 million years ago, during the late Cretaceous period in what is now the Gobi Desert in Mongolia.

      Prior analysis of Shuvuuia's fossilized eye bones revealed that it had large eyes that were specialized for seeing in dim light. But at the time, little was known about dinosaur adaptations for nocturnal activity. In a new study presented May 7, 2021 in Science, researchers looked at skulls from dozens of species of extinct theropods and modern birds, the only theropod lineage that survived to the present.

      By comparing dinosaurs' fossilized eye and ear structures with those in living animals that have nocturnal habits, the researchers were able to see if a dinosaur was adapted for day or night activity.

        Soft tissue is rarely preserved in the fossil record, but paleontologists can find clues about dinosaurs' eyes and vision in the bones that form a circle in the eye socket, known as the scleral ring. Scleral rings are found in many vertebrates (including extinct dinosaurs), and the diameter of this ring reveals the maximum width that an animal's pupil can dilate, hinting at their ability to see in low light, said lead study author Dr. Jonah Choiniere, University of the Witwatersrand in Johannesburg.  

     But nighttime hunting doesn't just depend on having good eyesight; specialized hearing is also key. So the researchers examined ear anatomy in 88 bird species and 17 extinct fossil theropods, using computed X-ray tomography (CT) scans to construct digital 3D models of the animals' skulls. They paid close attention to the cochlea, the part of the inner ear canal that holds sensory receptors for picking up sound waves. Decades of previous research had shown that the length of this canal is closely linked to how well animals can hear, and the length of Shuvuuia's ear canal suggested that its hearing would have been "off the charts," Dr. Choiniere said.

      "Shuvuuia had proportionally longer cochlear ducts than even the bird with the best hearing, the barn owl," Dr. Choiniere continued. What's more, the size of Shuvuuia's scleral rings showed that it also possessed "incredible night vision — better than any living bird we measured," he added. 

      The combination of light-sensitive eyes and superior hearing suggested that Shuvuuia would have been highly effective at detecting and ambushing prey at night, as owls do. By comparison, the theropod Velociraptor, which lived in the Gobi Desert alongside Shuvuuia, had an intermediate eye shape, "and was probably more twilight-active," said study co-author Dr. Lars Schmitz, W.M. Keck Science Department at Scripps College, CA. This is the first time that such extreme specializations for hearing and vision have been documented in an extinct dinosaur; in combining vision with hearing, the study also provides the best evidence for nocturnal behavior in dinosaurs, Dr. Schmitz said. 

     With a "hodgepodge body" Shuvuuia was an odd-looking dinosaur, and though it's related to fearsome meat-eating theropods such as Velociraptor and Tyrannosaurus rex, "it's totally unlike them," Dr. Choiniere said. "It's got a lightly built jaw, and its teeth look like tiny grains of basmati rice. It's got this massive eye, but the beak is very small," he said. Shuvuuia's forelimbs were powerful and bulky, tipped with a huge claw like an aardvark's. Capping off this hodgepodge of features was a pair of long, slender hind legs that were built for running. Shuvuuia deserti may have preyed on nocturnal desert insects. Shuvuuia deserti may have preyed on nocturnal desert insects. 

      However strange its body may have looked, these traits may have made Shuvuuia a better nighttime hunter. Some modern mammals that live in arid desert environments, as Shuvuuia did, combine lengthy hind limbs with digging forelimbs, "and they often have really good night vision and hearing," which helps them track and catch hard-to-find prey, Dr. Choiniere said. Burrowing desert prey would also be an easy meal for Shuvuuia to dig up with its powerful forearms. "This observation that Shuvuuia could have operated at night makes a lot of sense in light of the rest of the adaptations," he said. "It puts those into perspective and allows us to think it would have fit into a desert ecosystem today really well." 

      Animals that live together in the same geographical location often require the same resources in order to survive, but they can share them by being either night owls or early birds. Dinosaurs likely did this as well, and this study is just the beginning of paleontologists' discoveries of nocturnal and daytime preferences in these extinct animals and how those preferences might have affected their habits and behavior, Dr. Schmitz said. "That's something that we really don't understand well yet in the fossil record, but we know from looking at living species," he said. "I think there are some exciting discoveries waiting to be made."

         I wonder why we usually use birds to define early morning or late night behaviors. Which are you?

Rudists, Nudists, and Buddhists

     Although we have already discussed rudist (not rudest) clams here at PEOTS, new research about these reef builders of the Cretaceous was just published in February, 2020, warranting another look. Plus, I like the "Rudists, Nudists, and Buddhists" title. Rudists colonizing in zen-like seas? Count us in. 

        The earth turned faster at the end of the Cretaceous than it does today, rotating 372 times a year, compared to the current 365 1/4, according to a new study of fossil rudist shells. The research also shows a day lasted only 23.5 hours, according to the new study in American Geophysical Union's journal Paleoceanography and Paleoclimatology.

     The ancient mollusk, from an extinct and quite diverse group known as rudist clams, grew fast, laying down daily growth rings. The new study used lasers to sample minute slices of shell and count the growth rings with great accuracy. The growth rings allowed the researchers to determine the number of days in a year and more accurately calculate the length of a day 70 million years ago. The new measurement informs models of how the Moon formed and how close to Earth it has been over the 4.5-billion-year history of the Earth-Moon gravitational dance.

     The high resolution obtained in the new study combined with the fast growth rate of the ancient bivalves revealed unprecedented detail about how the animal lived and the water conditions it grew in, down to a fraction of a day.

     "We have about four to five datapoints per day, and this is something that you almost never get in geological history. We can basically look at a day 70 million years ago. It's pretty amazing," said Dr.  Niels de Winter, an analytical geochemist at Vrije Universiteit Brussel and the lead author of the new study.

     Climate reconstructions of the deep past typically describe long term changes that occur on the scale of tens of thousands of years. Studies like this one give a glimpse of change on the timescale of living things and have the potential to bridge the gap between climate and weather models.

     Chemical analysis of the shell indicates ocean temperatures were warmer in the Late Cretaceous than previously appreciated, reaching 40 degrees Celsius (104 degrees Fahrenheit) in summer and exceeding 30 degrees Celsius (86 degrees Fahrenheit) in winter. The summer high temperatures likely approached the physiological limits for mollusks, de Winter said.

     "The high fidelity of this data-set has allowed the authors to draw two particularly interesting inferences that help to sharpen our understanding of both Cretaceous astrochronology and rudist palaeobiology," said Dr. Peter Skelton, a retired paleobiologist at the Open University and a rudist expert unaffiliated with the new study.

    The new study analyzed a single individual that lived for over nine years in a shallow seabed in the tropics -- a location which is now, 70-million-years later, dry land in the mountains of Oman.

     "Torreites sanchezi mollusks look like tall pint glasses with lids shaped like bear claw pastries. The ancient mollusks had two shells, or valves, that met in a hinge, like asymmetrical clams, and grew in dense reefs, like modern oysters. They thrived in water several degrees warmer worldwide than modern oceans."

     In the late Cretaceous, rudists like T. sanchezi dominated the reef-building niche in tropical waters around the world, filling the role held by corals today. They disappeared in the same event that killed the non-avian dinosaurs 66 million years ago.

     "Rudists are quite special bivalves. There's nothing like them living today," de Winter said. "In the late Cretaceous especially, most of the reef builders are these bivalves. So they really took on the ecosystem building role that the corals have today."

     The new method focused a laser on small bits of shell, making holes 10 micrometers in diameter, or about as wide as a red blood cell. Trace elements in these tiny samples reveal information about the temperature and chemistry of the water at the time the shell formed. The analysis provided accurate measurements of the width and number of daily growth rings as well as seasonal patterns. The researchers used seasonal variations in the fossilized shell to identify years.

     The new study found the composition of the shell changed more over the course of a day than over seasons, or with the cycles of ocean tides. The fine-scale resolution of the daily layers shows the shell grew much faster during the day than at night.

     "This bivalve had a very strong dependence on this daily cycle, which suggests that it had photosymbionts," de Winter said. "You have the day-night rhythm of the light being recorded in the shell."

     This result suggests daylight was more important to the lifestyle of the ancient mollusk than might be expected if it fed itself primarily by filtering food from the water, like modern day clams and oysters, according to the authors. De Winter said the mollusks likely had a relationship with an indwelling symbiotic species that fed on sunlight, similar to living giant clams, which harbor symbiotic algae.

     "Until now, all published arguments for photosymbiosis in rudists have been essentially speculative, based on merely suggestive morphological traits, and in some cases were demonstrably erroneous. This paper is the first to provide convincing evidence in favor of the hypothesis," Skelton said, but cautioned that the new study's conclusion was specific to Torreites and could not be generalized to other rudists.

     De Winter's careful count of the number of daily layers found 372 for each yearly interval. This was not a surprise, because scientists know days were shorter in the past. The result is, however, the most accurate now available for the late Cretaceous, and has a surprising application to modeling the evolution of the earth-moon system.

     The length of a year has been constant over earth's history, because earth's orbit around the sun does not change. But the number of days within a year has been shortening over time because days have been growing longer. The length of a day has been growing steadily longer as friction from ocean tides, caused by the moon's gravity, slows earth's rotation.

    The pull of the tides accelerates the moon a little in its orbit, so as earth spin slows, the moon moves farther away. The moon is pulling away from earth at 3.82 centimeters (1.5 inches) per year. Precise laser measurements of distance to the moon from earth have demonstrated this increasing distance since the Apollo space program left helpful reflectors on the moon's surface.

     But scientists conclude the moon could not have been receding at this rate throughout its history, because projecting its progress linearly back in time would put the moon inside the earth only 1.4 billion years ago. Scientists know from other evidence that the Moon has been with us much longer, most likely coalescing in the wake of a massive collision early in Earth's history, over 4.5 billion years ago. So the Moon's rate of retreat has changed over time, and information from the past, like a year in the life of an ancient clam, helps researchers reconstruct that history and model of the formation of the moon.

       Rudists' growth patterns and rates provide great data for models from the Cretaceous.

Have you encountered any rudists in your fossil meanderings around the earth?
Steph

Vinicunca Rainbow Mountain in the Andes of Peru: Dr. Seussian Stripes

      The "Rainbow in the Mountain" of Vinicunca in the Andes in Peru is so remote, it is hard to locate on Peruvian maps. Vinicunca doesn't yet have a Wikipedia page (as of today). But, the rainbow will blow you away.

       Located in a remote part of the Andes, somewhere near Cusco, (or Cuzco), Peru, the magical sedimentary layers appear unreal.

      I looked at a few blogs and guided trips to convince myself it really is real.

 From the little geologic research I could find about the area, the Permian formations with their distinct colors of red, ochre, and turquoise sandstones and (possibly) overlying Cretaceous, limestone layers create a wondrous landscape for alpaca, llamas, and horses.

The herding communities in the region constitutes one of the few remaining pastoralist societies in the world. High mountain trails are used by these herders to trade with agricultural communities at lower elevations.

I will see if I can locate the Rainbow Mountain of Vinicunca on Google Earth in the morning. 

Have a go if you'd like!

{It's been a long day. The state of emergency declared in Ethiopia means Zoë will likely be coming stateside in the next 30 days. We just don't know when.}

One more look at the Seussical stripes of Rainbow Mountain in Peru!

Steph

Update: Google Earth view of Rainbow Mountain or Vinicunca

Mammals Evolved Three Times Faster after Dinosaur Extinction

     Our ancestors evolved three times faster in the 10 million years after the extinction of the dinosaurs than in the previous 80 million years, according to University College of London researchers.

     The research team found the speed of evolution of placental mammals (a group that today includes about 5000 species including humans) was constant before the extinction event but exploded after, resulting in the varied groups of mammals we see today.

     Lead (not lead ;-)) researcher, Dr. Thomas Halliday said: "Our ancestors, the early placental mammals, benefitted from the extinction of non-avian dinosaurs and dwindling numbers of competing groups of mammals. Once the pressure was off, placental mammals suddenly evolved rapidly into new forms."

     "In particular, we found a group called Laurasiatheria quickly increased their body size and ecological diversity, setting them on a path that would result in a modern group containing mammals as diverse as bats, cats, rhinos, whales, cows, pangolins, shrews and hedgehogs."

        Laurasiatheria is a superorder of placental mammals believed to have originated on the northern supercontinent of Laurasia. Thus it was the northern landmasses that produced much of the mammal explosion.

     The team found that the last common ancestor for all placental mammals lived in the late Cretaceous period, about three million years before the non-avian dinosaurs became extinct 66 million years ago. This date is about 20 million years younger than suggestions from previous studies which used molecular data from living mammals and assumed a near-constant rate of evolution.

     In this study the researchers analysed fossils from the Cretaceous to the present day, and used the dates of their occurrence in the fossil record to estimate the timing of divergences based on an updated tree of life. The new tree was released in 2015 and has the largest representation of Paleocene mammals to date.

     The scientists measured all the small changes in the bones and teeth of 904 placental fossils and mapped the anatomical differences between species on the tree of life. From measuring the number of character changes over time for each branch, they found the average rate of evolution for early placental mammals both before and after the dinosaur extinction event. They compared the average rate of evolution over the geological stages before the extinction and the geological stages after to see what impact it had.

     Senior author, Professor Anjali Goswami said, "Our findings refute those of other studies which overlooked the fossils of placental mammals present around the last mass extinction. Using rigorous methods, we've successfully tracked the evolution of early placental mammals and reconstructed how it changed over time. While the rate differed between species, we see a clear and massive spike in the rates of evolution right after the dinosaurs become extinct, suggesting our ancestors greatly benefitted from the demise of the dinosaurs. The huge impact of the dinosaur extinction on the evolution of our ancestors really shows how important this event was in shaping the modern world."

      Professor Paul Upchurch, co-author of the study, added: "Our large and refined data set allows us to build a clearer picture of evolutionary history. We plan on using it to study other large-scale evolutionary patterns such as how early placental mammals dispersed across the continents via land bridges that no longer exist today."

       I'd like to take that land bridge from South America to Africa in the southern land masses of Gondwanaland. 

      How about you? Does "Reunite Gondwanaland!" ring true to you?

Steph

A Swimming Dinosaur in the Kem Kem Beds: Spinosaurus didn't Dance the Can-Can but Sailed Along in the Water

     Spinosaurus, a large, swimming, fish-eating dinosaur of the Cretaceous period had a large sail on its back. It has been described as the "biggest, baddest predator to walk and swim on earth" by National Geographic.

        In the above reconstruction from Davide Bonadonna for National Geographic, Spinosaurus or "spine lizard" is shown in two poses: catching a fish underwater and straining its head above the water. As a fellow swimmer, the second pose is unrealistic. Straining its neck like that is an untenable swimming position; when turning its head it would surely keep its head closer to the water or else visit the dino masseuse frequently.

         Spinosaurus spines and the flesh in between the spines creating the sail are one of the biggest mysteries of this bigger-than-Tyrannosaurus rex dinosaur (over 50 feet long) discovered in the Kem Kem beds of Morocco:

     The long spines protruding from the vertebrae are up to eight times the size of the vertebrae themselves:

     Various hypotheses for the sail's purpose are a thermal regulating structure, a device for sailing in the water, a place for stored fat, and a structure for showing interest in mating. It may have also served a combination of these functions. I just don't understand what the flap is all about . . .;-)

     The head of Spinosaurus includes a jaw which does not handle torsion well:

      What a colorful creature ;-):

And, my, what big teeth "Mr. Big" had:

      Those teeth could sink into 8-foot lungfish, 13-foot coelacanths, 25-foot sawfish, and similarly outsize turtles also found in the Kem Kem beds.

      The National Geographic link describes the discovery of the bones as well as the recreation of the dinosaur's body for an exhibit opening this month in D.C.


       What's your idea for the Spinosaurus sail function?

       Are you dancing the can-can about the Kem Kem find?

Swimmingly,

Steph

The Fort on a cold, fall night. Waugh!

E-femur-al Find: Largest Dinosaur Bone Discovered in Argentina

    The discovery of the largest dinosaur bone in Argentina is the source of an e-femur-al delight today. It is nearly 8 feet long! The dinosaur, as yet unnamed, belongs to the class of dinosaurs called titanosaurs, due to their large size:

      The bones were discovered 160 km from Trelew, Patagonia, Argentina:

     Here are a couple of links to the announcement from earlier this week:

Titanosaur Femur Found--7.9 feet long

Patagonian Dinosaur Bones Found


     These vegetarian dinosaurs weighed as much as 14 full grown elephants. That's a lot of plants consumed. They lived during the Cretaceous Period, about 95 m. y. ago, represented below:

     What would you name the new species of dinosaur? Here's a link to the names of other Patagonian dinosaurs for inspiration:

             Patagonian Dinosaurs

Can you top Piatnitzkysaurus Floresi?

E-femur-ally,

Word Woman (Scientific Steph)

Bonus random-dot stereogram or autostereogram: What animal do you see?

Bonus opalized wood:

Bonus Australian Opal

        Hmmmm, maybe a week on opals may be in our future, o pals ;-).