Author Topic: Tyrannosaurids and Other Big Ancient Predators  (Read 490 times)

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Tyrannosaurids and Other Big Ancient Predators
« on: March 16, 2016, 06:12:53 AM »
It looks like the previous thread on this topic has been lost in database limbo, perhaps never to return. So, onward.  :)

A new early species of tyrannosaur has been found, which helps fill in the story of the evolution of the mighty beasts. "Timurlengia euotica: New Species of Tyrannosaur Discovered in Uzbekistan" | Sci-News

Quote

A reconstruction of Timurlengia euotica, named for the charismatic Central Asian ruler Tamerlane,
shows the species’ long, slender legs, large head and teeth built sharp like a steak knife.
Image credit: Todd Marshall

Timurlengia euotica lived during the Cretaceous period, approximately 90 million years ago, according to an international team of paleontologists led by Dr. Steve Brusatte from the University of Edinburgh, UK.

This species fills a 20 million year gap in the fossil record of tyrannosaurs — the iconic group of dinosaurian carnivores that includes T. rex and Albertosaurus, and provides key insights into how the group evolved.

Timurlengia euotica’s skull was much smaller than that of T. rex, indicating that it did not grow to the same enormous size,” Dr. Brusatte and his colleagues said.

“However, key features of its skull reveal that its brain and senses were already highly developed.”

The new species was about the size of a horse, and could weigh up to 250 kg. It had long legs and a skull studded with sharp teeth, and was likely a fast runner.

[Continues . . .]
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Re: Tyrannosaurids and Other Big Ancient Predators
« Reply #1 on: June 09, 2017, 03:36:04 PM »
A cool addition to our ideas about one of the families of big, scary ancient reptiles.

"Study casts doubt on the idea of 'big fluffy T. rex'" | BBC

Quote
Despite its ancestors having feathers, Tyrannosaurus rex most likely had scaly skin, according to fossil evidence.

Researchers say the huge predator had scales much like modern reptiles rather than feathers or fluff.

The dinosaur may have ditched its feathers because it no longer needed insulation when it reached gigantic proportions, they propose.

But the findings are unlikely to end the long-running debate about the physical appearance of T. rex.

We don't need to throw out the image of a big fluffy T. rex quite yet, argued one palaeontologist.

Whether T.rex was clad in scales, feathers or both, has long been a mystery, largely due to a lack of fossil evidence.

Primitive feathers have been identified in some members of the Tyrannosaur group, leading to speculation that the king of reptiles also sported feathers.

In the latest twist, researchers analysed skin impressions from a T.rex skeleton known as Wyrex, unearthed in Montana.

They also looked at relatives that roamed during the Late Cretaceous in Asia and other parts of North America, including Albertosaurus and Gorgosaurus.

Skin patches from the neck, pelvis and tail of Wyrex show scaly, reptilian-like skin, says a team led by Dr Phil Bell of the University of New England, Australia.

[Continues . . .]

The full paper is available for free: "Tyrannosauroid integument reveals conflicting patterns of gigantism and feather evolution" | Biology Letters

Quote
Abstract

Recent evidence for feathers in theropods has led to speculations that the largest tyrannosaurids, including Tyrannosaurus rex, were extensively feathered. We describe fossil integument from Tyrannosaurus and other tyrannosaurids (Albertosaurus, Daspletosaurus, Gorgosaurus and Tarbosaurus), confirming that these large-bodied forms possessed scaly, reptilian-like skin. Body size evolution in tyrannosauroids reveals two independent occurrences of gigantism; specifically, the large sizes in Yutyrannus and tyrannosaurids were independently derived. These new findings demonstrate that extensive feather coverings observed in some early tyrannosauroids were lost by the Albian, basal to Tyrannosauridae. This loss is unrelated to palaeoclimate but possibly tied to the evolution of gigantism, although other mechanisms exist.
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jumbojak

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Re: Tyrannosaurids and Other Big Ancient Predators
« Reply #2 on: June 11, 2017, 11:25:07 AM »
I just can't picture a feathered Rex. If it wasn't for the tiny arms I might be willing to accept it but the flapping would just be ridiculous.
 

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Re: Tyrannosaurids and Other Big Ancient Predators
« Reply #3 on: June 11, 2017, 02:58:38 PM »
I think the 'big, fluffy Tyrannosaurus rex' thing is a bit of an overstatement. Most of the illustrations I've seen have been along the lines of the image below:





Anyway, a slightly older item that belongs in this thread: "New dinosaur species sheds light on evolution, provides facial makeover for tyrannosaurs" | ScienceDaily

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An investigation by a team of scientists from Australia, Louisiana, Montana, New Mexico, and Wisconsin has identified and named a new species of the tyrannosaur clan: Daspletosaurus horneri -- "Horner's Frightful Lizard."

The species is named for renowned dinosaur paleontologist John "Jack" R. Horner, formerly curator at the Museum of the Rockies (MOR) in Bozeman, Montana. The tyrannosaur's name honors his discoveries of numerous dinosaur fossils and his mentorship of so many students that launched them to accomplished scientific careers. The type (name-bearing) specimens are stored in the research collections of the MOR.

The research is led by Thomas Carr, a professor in Carthage College's Biology Department and an expert on the evolution and growth of Tyrannosaurus rex and its closest relatives, collectively called tyrannosaurs.

[. . .]

In addition to adding a new species to the tyrannosaur family tree, the team's research provides new information about the mode of evolution and life appearance of tyrannosaurs -- specifically the face. This latest study, published today in Nature Publishing Group's Scientific Reports, found evidence for a rare, nonbranching type of evolution in tyrannosaurs and that tyrannosaurs had scaly, lipless faces and a highly touch-sensitive snout.

Carr said: "Daspletosaurus horneri was the youngest, and last, of its lineage that lived after its closest relative, D. torosus, which is found in Alberta, Canada. The close evolutionary relationship between the species taken with their geographic proximity and their sequential occurrence suggests that together they represent a single lineage that changed over geological time, where D. torosus has morphed into D. horneri."

[Continues . . .]

The full paper is available for free: "A new tyrannosaur with evidence for anagenesis and crocodile-like facial sensory system" | Scientific Reports

Wikipedia: Anagenesis

Quote
Abstract:

A new species of tyrannosaurid from the upper Two Medicine Formation of Montana supports the presence of a Laramidian anagenetic (ancestor-descendant) lineage of Late Cretaceous tyrannosaurids. In concert with other anagenetic lineages of dinosaurs from the same time and place, this suggests that anagenesis could have been a widespread mechanism generating species diversity amongst dinosaurs, and perhaps beyond.

We studied the excellent fossil record of the tyrannosaurid to test that hypothesis. Phylogenetic analysis places this new taxon as the sister species to Daspletosaurus torosus. However, given their close phylogenetic relationship, geographic proximity, and temporal succession, where D. torosus (~76.7–75.2 Ma) precedes the younger new species (~75.1–74.4 Ma), we argue that the two forms most likely represent a single anagenetic lineage. Daspletosaurus was an important apex predator in the late Campanian dinosaur faunas of Laramidia; its absence from later units indicates it was extinct before Tyrannosaurus rex dispersed into Laramidia from Asia. In addition to its evolutionary implications, the texture of the facial bones of the new taxon, and other derived tyrannosauroids, indicates a scaly integument with high tactile sensitivity. Most significantly, the lower jaw shows evidence for neurovasculature that is also seen in birds.



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Re: Tyrannosaurids and Other Big Ancient Predators
« Reply #4 on: June 11, 2017, 03:16:47 PM »
Still looks plenty fluffy to me, and I like it! 
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Re: Tyrannosaurids and Other Big Ancient Predators
« Reply #5 on: June 11, 2017, 04:02:28 PM »
More like scruffy than fluffy. I suppose I can live with that.
 

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Re: Tyrannosaurids and Other Big Ancient Predators
« Reply #6 on: June 11, 2017, 05:26:21 PM »
I'd bet it tasted like chicken.
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Re: Tyrannosaurids and Other Big Ancient Predators
« Reply #7 on: June 11, 2017, 08:31:07 PM »
I always thought of something more like the feathers of a penguin or kiwi, smallish and tight.

Just can't work out what it is chasing in that pic.
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Re: Tyrannosaurids and Other Big Ancient Predators
« Reply #8 on: June 12, 2017, 01:35:52 AM »
Quote from: Fernanda
I'd bet it tasted like chicken.

You kill one and we'll cook it,

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Re: Tyrannosaurids and Other Big Ancient Predators
« Reply #9 on: June 12, 2017, 02:51:55 PM »
Quote from: Fernanda
I'd bet it tasted like chicken.

You kill one and we'll cook it,

Are today's weapons allowed? :P

I just find it rather funny that dinosaurs used to eat our rat-like ancestors, now we raise and eat their descendants. In fact, I ate a dinosaur for lunch today. :yum: 
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Re: Tyrannosaurids and Other Big Ancient Predators
« Reply #10 on: July 05, 2017, 05:08:05 AM »
The illustration is of necessity dependent on the artist's imagination. I like it, though. Smile for the camera!

"Paleo Profile: The Large Ancestor Lizard" | Scientific American

Quote


Razanandrongobe has a nice lunch. Image credit: Fabio Manucci

In 2006, when paleontologist Simone Maganuco and colleagues named Razanandrongobe sakalavae, there wasn't very much to go on. All they had was a part of the front of the jaw and some teeth from some sort of archosaur - one of the ruling reptiles that included dinosaurs and crocodiles among their ranks. Now, thanks to some new fossils, we know a little bit more about what this blunt-toothed carnivore looked like.

What the whole body of Razanandrongobe looked like is still unclear. The known material is restricted to the jaws. But, Cristiano Dal Sasso, Maganuco, and coauthors report, it's enough to narrow down the identity of this chomper to a branch of ancient crocodiles called mesoeucrocodylians. But given that paleo fans love superlative meat eaters, what's making headlines is that this old croc was a carnivorous giant.

Based upon the available material, Dal Sasso and colleagues estimate that Razanandrongobe was the largest Jurassic croc in the terrestrial realm, far larger than today's Nile crocodile. More than that, the deep jaws and thick, coarsely-serrated teeth of Razanandrongobe hint that this croc could make the most of carcasses, crushing bone and other hard parts just like our old favorite Tyrannosaurus is thought to have done. With any luck, future fieldwork will reveal more of this exceptional Jurassic crusher.

[Continues . . .]

The BBC has a write-up as well: "Giant croc had teeth like a T. rex"

The full paper is available for free: "Razanandrongobe sakalavae, a gigantic mesoeucrocodylian from the Middle Jurassic of Madagascar, is the oldest known notosuchian" | PeerJ

Quote
Abstract


Razanandrongobe sakalavae Maganuco, Dal Sasso & Pasini, 2006 is a large predatory archosaur from the Middle Jurassic (Bathonian) of the Mahajanga Basin, NW Madagascar. It was diagnosed on the basis of teeth and a fragmentary maxilla, but its affinities were uncertain. Here we describe new cranial remains (above all, an almost complete right premaxilla and a caudally incomplete left dentary) that greatly improve our knowledge on this enigmatic species and reveal its anatomy to be crocodylomorph.

The right premaxilla indicates that the rostrum was deep, wide, and not pointed; it bears five teeth that are sub-vertical and just slightly curved lingually; the mesial teeth are U-shaped in cross-section and have serrated carinae on the lingual side; the aperturae nasi osseae (external bony nares) are confluent and face rostrally; and there is no lateral groove at the premaxillomaxillary suture for reception of a hypertrophied lower caniniform tooth. The preserved portion of the left dentary has an edentulous tip and bears eight large mandibular teeth of which the mesial (1–3) are the largest, but none is a hypertrophied caniniform tooth; the mandibular (dentary) symphysis extends caudally to the level of the third tooth; the splenial is not preserved, but its sutural marks on the dentary indicate that it contributed to the mandibular symphysis for at least 20% of the symphyseal length in dorsal aspect.

On the basis of this new data, some previously uncertain features of the holotype maxilla—such as the margin of the suborbital fenestra, the contact surfaces for the palatine, the ectopterygoid, and the jugal—are now apparent. Testing of the phylogenetic position of the species within Crocodylomorpha indicates that R. sakalavae is a mesoeucrocodylian. It also represents one of the earliest events of exacerbated increase in body size along the evolutionary history of the group. In addition, it is by far the oldest notosuchian. A cranial reconstruction of this gigantic predator is also attempted here. The very robust jaw bones of R. sakalavae, coupled with its peculiar dentition, strongly suggest a diet that included hard tissue such as bone and tendon.
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Re: Tyrannosaurids and Other Big Ancient Predators
« Reply #11 on: August 05, 2017, 07:00:25 AM »
The results of a new analysis indicate that Tyrannosaurus rex when fully grown would have been relatively slow moving; its bones wouldn't have been able to withstand the mechanical stress of running.

"Tyrannosaurus rex couldn't run, says new research" | Phys.Org

Quote
It is a classic chase scene in modern cinematic history. The image of a rampant Tyrannosaurus rex (T. rex) chasing Jeff Goldblum as he sits injured in the back of a 4x4 vehicle in Stephen Spielberg's original film adaptation of Jurassic Park.

But could a T. rex actually move that fast, or even run at all?

New research from the University of Manchester says the sheer size and weight of T. rex means it couldn't move at high speed, as its leg-bones would have buckled under its own weight load.

The research, published by journal PeerJ, looks extensively into the gait and biomechanics of the world's most famous Dinosaur and, using the latest high performance computing technology from N8 High Performance Computing (HPC), has created a new simulation model to test its findings.

Led by Professor William Sellers from the School of Earth and Environmental Sciences, the researchers have combined two separate biomechanical techniques, known as multibody dynamic analysis (MBDA) and skeletal stress analysis (SSA), into one simulation model, creating a new more accurate one.

Prof Sellers says the results demonstrate any running gaits for T. rex would probably lead to 'unacceptably high skeletal loads'. Meaning, in layman's terms, any running would simply break the dinosaur's legs. This contradicts the running speeds predicted by previous biomechanical models which can suggest anything up to 45mph.

[Continues . . .]

The full paper is available for free: "Investigating the running abilities of Tyrannosaurus rex using stress-constrained multibody dynamic analysis" | PeerJ

Quote
Abstract:


The running ability of Tyrannosaurus rex has been intensively studied due to its relevance to interpretations of feeding behaviour and the biomechanics of scaling in giant predatory dinosaurs. Different studies using differing methodologies have produced a very wide range of top speed estimates and there is therefore a need to develop techniques that can improve these predictions.

Here we present a new approach that combines two separate biomechanical techniques (multibody dynamic analysis and skeletal stress analysis) to demonstrate that true running gaits would probably lead to unacceptably high skeletal loads in T. rex. Combining these two approaches reduces the high-level of uncertainty in previous predictions associated with unknown soft tissue parameters in dinosaurs, and demonstrates that the relatively long limb segments of T. rex—long argued to indicate competent running ability—would actually have mechanically limited this species to walking gaits. Being limited to walking speeds contradicts arguments of high-speed pursuit predation for the largest bipedal dinosaurs like T. rex, and demonstrates the power of multiphysics approaches for locomotor reconstructions of extinct animals.
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Re: Tyrannosaurids and Other Big Ancient Predators
« Reply #12 on: August 05, 2017, 07:18:46 AM »
^

I remember seeing stuff like that years ago. Wish I could remember more but I seem to remrmber one TV docu scaled up from ostrich legs, adding size/weight and letting software "tailor" the legs and gait to suit the stresses, inertia, momentum etc.. Yup, definitely got slower and shorter paced as the ratio increased.

Pity someone does not do, or publish, a metastudy on the subject.
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Re: Tyrannosaurids and Other Big Ancient Predators
« Reply #13 on: August 05, 2017, 07:26:42 AM »
I suppose this, from 2007, is one of those "earlier biomechanical models"!



That's better, but now I can't find the NS article!
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Re: Tyrannosaurids and Other Big Ancient Predators
« Reply #14 on: August 05, 2017, 09:13:30 AM »
We should genetically engineer dinosaurs that can run and have thick, armoured shells then send them into war zones


...yeah...
But, uh...well there it is.
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