Spinosaurid dinosaur species size comparison


This 20 May 2019 video is about Spinosauridae dinosaur species size comparison.

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Jurassic sauropod dinosaur, from quadrupedal to bipedal


GROWING UP As Mussaurus patagonicus grew, the long-necked dinosaur’s center of mass shifted back toward its hips and tail, letting it go from a four-legged to two-legged gait even as it ballooned from the size of a chick to that of a rhinoceros. A. Otero et al./Scientific Reports 2019

By John Pickrell, 5:00am, May 20, 2019:

This early sauropod went from walking on four legs to two as it grew

Center of mass shifts led to a rare change in walking style for a long-necked dinosaur relative

Most long-necked sauropods lumbered on four legs all their lives to support their titanic bulk. But an early relative of such behemoths as Brachiosaurus made the unusual transition from walking on four legs to two as it grew, a new study shows.

Diminutive at hatching, Mussaurus patagonicus (which means “mouse lizard”) began life walking on all fours. But by the time the 200-million-year-old plant eater reached its 6-meter-long adult size, it roamed what’s now Argentina on two legs.

The changing length of M. patagonicus’s arm bones relative to its body and its inward facing-palms as an adult had hinted at the transition. But for the first time, computer simulations based on a rich fossil record show how a shift in the creature’s center of gravity as it grew enabled a change to bipedal walking, researchers report May 20 in Scientific Reports.

Researchers took CT scans of fossil bones from six individual M. patagonicus — covering different stages of the species’ development, from 60-gram hatchlings the size of baby chickens to 1.5 metric ton adults the size of rhinoceroses. The researchers added virtual flesh to digitized bones to create 3-D models that allowed them to estimate both the weight and center of gravity of M. patagonicus at many different stages of its life.

Reconstructions of the hatchlings showed that the creature’s center of mass was so far forward that the dinosaurs could move around only by walking on all four legs, says Andrew Cuff, a paleontologist of the Structure and Motion Laboratory of the Royal Veterinary College in Hatfield, England.

As the dinos grew, their center of mass moved back toward their hips, allowing them to walk upright on two legs, Cuff and colleagues found. The transition “is incredibly rare,” he says. “We have struggled to find any other animals aside from humans that go through that transition…. Finding it in the fossil record is pretty exceptional.”

The results suggest these adult dinosaurs turned bipedal because their tail muscles became bulkier and heavier as they grew, moving their center of gravity backward, says Stephen Poropat, a paleontologist at Swinburne University of Technology in Melbourne, Australia, who was not involved in the research. “It is not the changing proportions of Mussaurus’s front legs that is necessitating this change from walking on four legs to walking on two legs as an adult,” he says.

As later long-necked dinos bulked up in size (SN Online: 9/4/14), going to two legs may no longer have been an option. Massive sauropods instead probably started on four legs like M. patagonicus and stayed that way, developing trunklike front legs to bear their weight. “What we gain from this [study] is that there may be a size limit of how big you can get being a biped in this group,” Cuff says.

Small Tyrannosaur relative discovered


This 6 May 2019 video from the USA says about itself:

I attended the press conference this morning at the Arizona Museum of Natural History where I volunteer in Mesa, AZ announcing a new species of tyrannosaur, Suskityrannus hazelea, which means Hazel’s Coyote Tyrant. Suski is the word for coyote in the Zuni language from the area where the discovery was made on the border of Arizona and New Mexico.

The speakers are Museum Director Tom Wilson, Hazel Wolfe (namesake), Paleontologist Doug Wolfe, Curator of Paleontology Dr. Robert McCord, Paleo Artist Benji Paysnoe, and Curator of Education Alison Stoltman. Dr. Sterling Nesbitt was just 16 years old when he discovered the first fossil specimens of this species while on a dig with Doug Wolfe and the Southwest Paleontological Society.

I can’t stress enough the importance that organizations like that have in promoting Citizen Science and how they have lead to many new discoveries. Please check out my video on Citizen Science at the link. It also features other dinosaur discoveries here in Arizona.

From Virginia Tech in the USA:

New 3-foot-tall relative of Tyrannosaurus rex

May 6, 2019

Summary: ‘Suskityrannus gives us a glimpse into the evolution of tyrannosaurs just before they take over the planet,’ said Sterling Nesbit.

A new relative of the Tyrannosaurus rex — much smaller than the huge, ferocious dinosaur made famous in countless books and films, including, yes, “Jurassic Park” — has been discovered and named by a Virginia Tech paleontologist and an international team of scientists.

The newly named tyrannosauroid dinosaur — Suskityrannus hazelae — stood roughly 3 feet tall at the hip and was about 9 feet in length, the entire animal only marginally longer than just the skull of a fully grown Tyrannosaurus rex, according to Sterling Nesbitt, an assistant professor with Department of Geosciences in the Virginia Tech College of Science. In a wild twist to this discovery, Nesbitt found the fossil at age 16 whilst a high school student participating in a dig expedition in New Mexico in 1998, led by Doug Wolfe, an author on the paper.

In all, Suskityrannus hazelae is believed to have weighed between 45 and 90 pounds. The typical weight for a full-grown Tyrannosaurus rex is roughly 9 tons. Its diet likely consisted of the same as its larger meat-eating counterpart, with Suskityrannus hazelae likely hunting small animals, although what it hunted is unknown. The dinosaur was at least 3 years old at death based on an analysis of its growth from its bones.

The fossil dates back 92 million years to the Cretaceous Period, a time when some of the largest dinosaurs ever found lived.

“Suskityrannus gives us a glimpse into the evolution of tyrannosaurs just before they take over the planet,” Nesbitt said. “It also belongs to a dinosaurian fauna that just proceeds the iconic dinosaurian faunas in the latest Cretaceous that include some of the most famous dinosaurs, such as the Triceratops, predators like Tyrannosaurus rex, and duckbill dinosaurs like Edmo[n]tosaurus.”

The findings are published in the latest online issue of Nature Ecology & Evolution. In describing the new find, Nesbitt said, “Suskityrannus has a much more slender skull and foot than its later and larger cousins, the Tyrannosaurus rex. The find also links the older and smaller tyrannosauroids from North America and China with the much larger tyrannosaurids that lasted until the final extinction of non-avian dinosaurs.

(Tyrannosaurus rex small arm jokes abound. So, if you’re wondering how small the arms of Suskityrannus were, Nesbitt and his team are not exactly sure. No arm fossils of either specimen were found, but partial hand claws were found. And, they are quite small. Also not known: If Suskityrannus had two or three fingers.)

Two partial skeletons were found. The first included a partial skull that was found in 1997 by Robert Denton, now a senior geologist with Terracon Consultants, and others in the Zuni Basin of western New Mexico during an expedition organized by Zuni Paleontological Project leader Doug Wolfe.

The second, more complete specimen was found in 1998 by Nesbitt, then a high school junior with a burgeoning interest in paleontology, and Wolfe, with assistance in collection by James Kirkland, now of the Utah Geological Survey. “Following Sterling out to see his dinosaur, I was amazed at how complete a skeleton was lying exposed at the site,” Kirkland said.

For much of the 20 years since the fossils were uncovered, the science team did not know what they had.

“Essentially, we didn’t know we had a cousin of Tyrannosaurus rex for many years,” Nesbitt said. He added the team first thought they had the remains of a dromaeosaur, such as Velociraptor. During the late 1990s, close relatives [of] Tyrannosaurus rex simply were not known or not recognized. Since then, more distant cousins of Tyrannosaurus rex, such as Dilong paradoxus, have been found across Asia.

The fossil remains were found near other dinosaurs, along with the remains of fish, turtles, mammals, lizards, and crocodilians. From 1998 until 2006, the fossils remain[ed] stored at the Arizona Museum of Natural History in Mesa, Arizona. After 2006, Nesbitt brought the fossils with him through various postings as student and researcher in New York, Texas, Illinois, and now Blacksburg. He credits the find, and his interactions with the team members on the expedition, as the start of his career.

“My discovery of a partial skeleton of Suskityrannus put me onto a scientific journey that has framed my career,” said Nesbitt, also a member of the Virginia Tech Global Change Center. “I am now an assistant professor that gets to teach about Earth history.”

The name Suskityrannus hazelae is derived from “Suski”, the Zuni Native American tribe word for “coyote,” and from the Latin word ‘tyrannus’ meaning king and ‘hazelae’ for Hazel Wolfe, whose support made possible many successful fossil expeditions in the Zuni Basin. Nesbitt said permission was granted from the Zuni Tribal Council to use the word “Suski”.

How some dinosaurs became birds, new research


This 2013 video says about itself:

Microraptor | Flying Dinosaur | Planet Dinosaur | BBC

Planet Dinosaur takes to skies, to investigate the perculiarities of winged dinosaurs. Microraptor had feathers for gliding but is it enough to escape from Sinornithosaurus?

From PLOS:

Running may have made dinosaurs’ wings flap before they evolved to fly

New evidence suggests that passive wing flapping may have arisen earlier than gliding flight

May 2, 2019

Before they evolved the ability to fly, two-legged dinosaurs may have begun to flap their wings as a passive effect of running along the ground, according to new research by Jing-Shan Zhao of Tsinghua University, Beijing, and his colleagues.

The findings, published in PLOS Computational Biology, provide new insights into the origin of avian flight, which has been a point of debate since the 1861 discovery of Archaeopteryx. While a gliding type of flight appears to have matured earlier in evolutionary history, increasing evidence suggests that active flapping flight may have arisen without an intermediate gliding phase.

To examine this key point in evolutionary history, Zhao and his colleagues studied Caudipteryx, the most primitive, non-flying dinosaur known to have had feathered “proto-wings.” This bipedal animal would have weighed around 5 kilograms and ran up to 8 meters per second.

First, the researchers used a mathematical approach called modal effective mass theory to analyze the mechanical effects of running on various parts of Caudipteryx’s body. These calculations revealed that running speeds between about 2.5 to 5.8 meters per second would have created forced vibrations that caused the dinosaur’s wings to flap.

Real-world experiments provided additional support for these calculations. The scientists built a life-size robot of Caudipteryx that could run at different speeds, and confirmed that running caused a flapping motion of the wings. They also fitted a young ostrich with artificial wings and found that running indeed caused the wings to flap, with longer and larger wings providing a greater lift force.

“Our work shows that the motion of flapping feathered wings was developed passively and naturally as the dinosaur ran on the ground,” Zhao says. “Although this flapping motion could not lift the dinosaur into the air at that time, the motion of flapping wings may have developed earlier than gliding.”

Zhao says that the next step for this research is to analyze the lift and thrust of Caudipteryx’s feathered wings during the passive flapping process.

Duck-billed dinosaurs, new research


This 2018 video is called Hadrosaurs Size Comparison.

From the University of Bristol in England:

Chewing versus sex in duck-billed dinosaurs

Evolutionary bursts led to weird and wonderful head crests

May 2, 2019

The duck-billed hadrosaurs walked the Earth over 90 million years ago and were one of the most successful groups of dinosaurs. But why were these 2-3 tonne giants so successful? A new study, published in Paleobiology, shows that their special adaptations in teeth and jaws and in their head crests were crucial, and provides new insights into how these innovations evolved.

Called the ‘sheep of the Mesozoic’ as they filled the landscape in the Late Cretaceous period, hadrosaurs walked on their hind legs and were known for their powerful jaws with multiple rows of extremely effective teeth. They also had hugely varied head display crests that signalled which species each belonged to and were used to attract mates. Some even trumpeted and tooted their special call, using nasal passages through the head crests.

Researchers from the Universities of Bristol and the Catalan Institute of Paleontology in Barcelona used a large database describing morphological variety in hadrosaur fossils and computational methods that quantify morphological variety and the pace of evolution.

Dr Tom Stubbs, lead author of the study and a researcher from Bristol’s School of Earth Sciences, said: “Our study shows that the unique hadrosaur feeding apparatus evolved fast in a single burst, and once established, showed very little change. In comparison, the elaborate display crests kept diversifying in several bursts of evolution, giving rise to the many weird and wonderful shapes.”

Professor Mike Benton, the study’s co-author from Bristol’s School of Earth Sciences, added, “Variation in anatomy can arise in many ways. We wanted to compare the two famous hadrosaur innovations, and by doing so, provide new insights into the evolution of this important dinosaur group. New numerical methods allow us to test these kinds of complex evolutionary hypotheses.”

“Our methods allowed us to identify branches on the hadrosaur evolutionary tree that showed rapid evolution in different parts of the skeleton,” said co-author Dr Armin Elsler. “When we looked at the jaws and teeth, we only saw fast evolution on a single branch at the base of the group. On the other hand, the bones that form the display crests showed multiple fast rate branches.”

Dr Albert Prieto-Márquez, co-author and world-leading expert on hadrosaurs from the Catalan Institute of Paleontology in Barcelona, added: “Our results suggest that evolution can be driven in different ways by natural selection and sexual selection. Hadrosaurs apparently fixed on a feeding apparatus that was successful and did not require massive modification to process their food. On the other hand, sexual selection drove the evolution of more complex crest shapes, and this is reflected by multiple evolutionary bursts.”

Aquatic ankylosaur dinosaur discovery?


This 21 April 2019 video says about itself:

An Aquatic Ankylosaur?

There were once some very strange dinosaurs, but one of the strangest may have been a species of small, possibly fish-eating aquatic ankylosaurLiaoningosaurus paradoxus.