Shaking the dinosaur family tree: How did 'bird-hipped' dinosaurs evolve? (2023)

Shaking the dinosaur family tree: How did 'bird-hipped' dinosaurs evolve? (1)

Researchers have conducted a new analysis of the origins of "bird-hipped" dinosaurs—the group which includes iconic species such as Triceratops—and found that they likely evolved from a group of animals known as silesaurs, which were first identified two decades ago.

The researchers, from the University of Cambridge and the Universidade Federal de Santa Maria in Brazil, were attempting to solve a long-standing mystery in paleontology: where the "bird-hipped" dinosaurs, or ornithischians, came from.

Currently, there is a gap of more than 25 million years in the fossil record, making it difficult to find the branch of the dinosaur family tree where ornithischians belong.

The researchers conducted an extensive analysis of early dinosaurs as well as silesaurs, a group named after Silesaurus, first described in 2003. The researchers suggest that silesaurs progressively modified their anatomy during the Late Triassic Period, so that they came to resemble ornithischians by the Early Jurassic Period.

However, these ornithischian ancestors have the hip structure of the "lizard-hipped" dinosaurs, or saurischians, suggesting that the earliest bird-hipped dinosaurs were in fact lizard-hipped. The results are reported in the Zoological Journal of the Linnean Society.

Dinosaurs originated in the Late Triassic period, about 225 million years ago, and dominated life on Earth until a mass extinction event 66 million years ago. Dinosaurs have fascinated us since they were first named as such by Richard Owen in 1842.

Shaking the dinosaur family tree: How did 'bird-hipped' dinosaurs evolve? (2)
(Video) WN@TL - Shaking the Dinosaur Family Tree. David Lovelace. 2017.07.05

The earliest discovered dinosaur remains were scrappy: odd-looking teeth and a few bones. By the latter half of the 19th century however, enough dinosaur remains had been found that a classification system was needed. Harry Seeley, who had been trained in Cambridge by Adam Sedgwick, developed such a classification of dinosaurs based primarily upon the shape of their hip bones: they were either saurischians (lizard-hipped) or ornithischians (bird-hipped). This classification, first published in 1888, proved reliable: all dinosaur discoveries seemed to slot neatly into one or other of these groupings.

However, in 2017, Professor David Norman from Cambridge's Department of Earth Sciences and his former Ph.D. students Matthew Baron and Paul Barrett argued that these dinosaur family groupings need to be rearranged, re-defined and re-named. In a study published in Nature, the researchers suggested that bird-hipped dinosaurs and lizard-hipped dinosaurs such as Tyrannosaurus evolved from a common ancestor, potentially overturning more than a century of theory about the evolutionary history of dinosaurs.

Controversy aside, it has long been recognized that the bird-hipped dinosaurs are anatomically distinct from all other types of dinosaurs, even though they have nothing to do with birds. But how they came to be has remained a long-standing problem.

"It seemed to be that they originated with all other dinosaurs in the Late Triassic but exhibited a unique set of features that could not be fitted into an evolutionary succession from their dinosaur cousins," said Norman, who is a Fellow of Christ's College. "It was as if they just suddenly appeared out of nowhere."

Recent work has begun to indicate a more varied and puzzling picture of ornithischian origins. From a phylogenetic perspective—how the dinosaur family tree branches over time—it is predicted that ornithischian remains should first appear in the fossil record about 225 million years ago.

Shaking the dinosaur family tree: How did 'bird-hipped' dinosaurs evolve? (3)
(Video) Shaking the Dinosaur Family Tree | University Place

"However, the more we've looked in rocks of that age, the less we've found," said Norman. "The first unarguable ornithischian remains date from less than 200 million years ago, meaning there is a 25+ million-year ornithischian gap. So far, all attempts to fill that gap have failed."

One solution to this conundrum can be traced back to a discovery in the early years of this century, when the skeleton of an unusual Late Triassic dinosaur-like animal was discovered in Poland. It was described by Jerzy Dzik and named Silesaurus (the "Silesian lizard").

Silesaurus has long slender legs that gave it an upright dinosaur-like posture—and its hip bones are arranged like a saurischian—but it seemed to have a toothless, beak-like region at the front of its lower jaw. This was not unlike the toothless beak-like structure known as a predentary that is found in all ornithischian dinosaur skulls, although the uniquely ornithischian predentary bone was not present.

Its teeth were also constricted at the top of the roots, and the crowns of the teeth were leaf-shaped in profile: a type of tooth shape seen in many early ornithischians. Dzik speculated about the possible ornithischian similarities of Silesaurus, but the suggestion was dismissed or ignored by most researchers.

In the years that followed, more Silesaurus-like creatures were discovered, mostly in South America. Many of these specimens were fragments, but the toothless tip of the lower jaw and the leaf-shaped teeth were common.

The accumulation of these specimens attracted the attention of several researchers. Their analyses suggested that silesaurs were close relatives of true dinosaurs. Either they were placed on a branch just before the origin of true dinosaurs or, in some instances, they appeared as a sister group to Ornithischia. In 2020, Mauricio Garcia and Rodrigo Müller from the Universidade Federal de Santa Maria in Brazil proposed that silesaur-like creatures could sit on the branch of Dinosauria that led to Ornithischia.

"This work attracted our attention in Cambridge," said Norman. "A few years ago, I devised a research project aimed directly at the problem of how the Ornithischia came to be, and Matt was the research student on the project."

(Video) PU Dinosaurs: Class 2 - THE DINOSAUR FAMILY TREE with Lindsay Kastroll

Norman and Barron began to collaborate with Rodrigo and Mauricio, enlarging the original analysis to include a range of ornithischian dinosaurs, as well as dinosaur ancestors. The outcome of their collaboration is a family tree that depicts silesaurs as a succession of animals on the stem of the branch leading to Ornithischia.

"Silesaurians progressively modified their anatomy during the Late Triassic, so that they come to resemble ornithischians," said Norman. "We have been able to trace this transition through the development of the toothless beak, the development of leaf-shaped coarse-edged teeth typical of those seen in the herbivorous ornithischians, modifications to the shoulder bones, changes in the proportions of the pelvic bones, and finally a restructuring of the muscle attachment areas on the hind legs."

The research suggests that ornithischians did not arise from nowhere. Rather, they first appeared in the Late Triassic in the guise of silesaurs that gradually rearranged their anatomy with the passage of time until recognizable ornithischians had evolved by the beginning of the Jurassic Period.

Shaking the dinosaur family tree: How did 'bird-hipped' dinosaurs evolve? (5)

However, there is another aspect to this explanation, which is that the earliest ornithischians of the Late Triassic had none of the anatomical characteristics of true ornithischians: they lacked a predentary and, most importantly, retained the early saurischian hip construction.

"So, the very earliest ornithischians were, technically, saurischian," said Norman. "From a taxonomic perspective, classifying silesaurs as early ornithischians seems counterintuitive. But, taking a Darwinian perspective, the unique anatomical characteristics of ornithischians had to evolve from somewhere, and where better than from their nearest relatives: their saurischian cousins."

More information:David B Norman et al, Taxonomic, palaeobiological and evolutionary implications of a phylogenetic hypothesis for Ornithischia (Archosauria: Dinosauria), Zoological Journal of the Linnean Society (2022). DOI: 10.1093/zoolinnean/zlac062

Journal information:Zoological Journal of the Linnean Society

, Nature

Provided byUniversity of Cambridge

(Video) Theory shakes up 130 years of dinosaur doctrine

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Did bird hipped dinosaurs evolve birds? ›

Living birds had common ancestors on the theropod lineage. Oddly, birds are derived from the "lizard-hipped" dinosaurs and not from the "bird-hipped" ornithischian dinosaurs.

What changes have been made to the dinosaur family tree? ›

The revised grouping of Ornithischia and Theropoda has been named Ornithoscelida, meaning 'bird-limbed'. In addition, a group of carnivorous dinosaurs called herrerasaurids, which have traditionally been classed as theropods, have been moved to join the sauropodomorphs within the Saurischia.

What dinosaurs were bird hipped? ›

ornithischian, any member of the large taxonomic group of herbivorous dinosaurs comprising Triceratops and all dinosaurs more closely related to it than to birds. The ornithischians (meaning “bird-hipped”) are one of the two major groups of dinosaurs, the other being the saurischians.

How did evolution lead to dinosaurs? ›

Dinosaurs arose from small dinosauromorph ancestors in the Triassic period, when the climate was harsh and dry. They faced "competition from the croc-line archosaurs for tens of millions of years, [but] finally prevailed when Pangaea began to split," Brusatte told Live Science.

How did dinosaurs evolve into birds? ›

During the course of their evolutionary history, the body size of some theropod groups gradually decreased - a trend that, together with many other changes to the skeleton, ultimately led to the appearance of birds. Paul says, 'In 1996 the first feathered dinosaur was announced and many others have come to light since.

When did birds evolve? ›

The ancestors of all today's birds evolved later, he says, between 65 and 53 million years ago, independently of the dinosaurs. This is the "big bang theory" of birds.

What is a dinosaur family called? ›

Understanding the seven major groups, theropods, sauropods, stegosaurs, ankylosaurs, ornithopods, ceratopsians, and pachycephalosaurs, is a first step to help the novice place a new dinosaur in the greater context, and also understand the history of life a little bit better.

How many families of dinosaurs are there? ›

To date, scientists have identified thousands of individual dinosaur species, which can be roughly assigned to 15 major families—ranging from ankylosaurs (armored dinosaurs) to ceratopsians (horned, frilled dinosaurs) to ornithomimids ("bird mimic" dinosaurs).

What is the dinosaur family? ›

In the old family tree, there are two major groups of dinosaurs: the bird-hipped ornithischian dinosaurs (such as duck-billed dinosaurs and stegosaurs) and the reptile-hipped saurischians, which include the theropods (such as Tyrannosaurus rex) and the sauropods (the long-necked, long-tailed herbivorous giants).

How many dinosaurs are there? ›

At present over 700 different species of dinosaurs have been identified and named.

When did saurischian dinosaurs evolve? ›

The saurischians and ornithischians separated as lineages perhaps 235 million to 240 million years ago during the Middle Triassic Period (242 million to 227 million years ago).

What did ornithischian dinosaurs evolve into? ›

The meat-eating theropods, which included the famous Tyrannosaurus rex, have evolved into the modern dinosaurs: birds. And the bird-hipped ornithischians, an assorted group of herbivorous dinosaurs, evolved some of the most bizarre anatomy known in evolutionary history.

Why did dinosaurs evolve before humans? ›

The environment allowed evolution to lead to the formation of dinosaurs. The environment wasn't conducive to a somewhat large warm-blooded mammal like us. When the conditions on the Earth changed mammals evolved into larger than they were at the time of the dinosaurs and we eventually came about.

How long did it take dinosaurs to evolve? ›

Dinosaurs evolved from their smaller ancestors in just a few million years and not the 10 million years or more scientists had suspected, according to a new study.

When did humans first evolve? ›

The first human ancestors appeared between five million and seven million years ago, probably when some apelike creatures in Africa began to walk habitually on two legs. They were flaking crude stone tools by 2.5 million years ago. Then some of them spread from Africa into Asia and Europe after two million years ago.

What would dinosaurs evolve into? ›

As dinosaurs morphed into birds, they shrank dramatically and adopted a more babylike skull shape. Shown left to right: Velociraptor, a dinosaur of the class that gave rise to birds; Archaeopteryx, often called the first bird; and a modern chicken and pigeon.

What animals did dinosaurs evolve into? ›

Modern birds descended from a group of two-legged dinosaurs known as theropods, whose members include the towering Tyrannosaurus rex and the smaller velociraptors.

Why did birds evolve beaks? ›

Abstract. The toothless beak of modern birds was considered as an adaption for feeding ecology; however, several recent studies suggested that developmental factors are also responsible for the toothless beak.

What was the first dinosaur? ›

The earliest dinosaurs for which we do have well-documented fossils are found in Late Triassic Ischigualasto Formation in northern Argentina. Skeletons discovered in these rock layers include the meat-eating dinosaurs Herrerasaurus and Eoraptor, as well as the plant-eating dinosaur Pisanosaurus.

What was the first bird? ›

The earliest known (from fossils) bird is the 150-million-year-old Archaeopteryx, but birds had evolved before then. A range of birds with more advanced features appeared soon after Archaeopteryx. One group gave rise to modern birds in the Late Cretaceous.

Is a bird a dinosaur? ›

Birds belong to the theropod group of dinosaurs that included T. rex. Theropods are all bipedal and some of them share more bird-like features than others. Archaeopteryx, discovered in 1861, was for a long time the only truly bird-like dinosaur – it's from the Late Jurassic era (150 million years ago).

What dinosaur has 5000 teeth? ›

Nigersaurus Temporal range: Aptian – Albian
Genus:†Nigersaurus Sereno et al., 1999
Species:†N. taqueti
Binomial name
†Nigersaurus taqueti Sereno et al., 1999
11 more rows

What were the 3 types of dinosaurs? ›

While scientists have complex ways of classifying dinosaurs, most people separate them into three groups: carnivores, herbivores, and omnivores. Let's learn more about these three types of dinosaurs.

What 2 dinosaurs are the same? ›

Some undergraduates also helped prepare the fossils once they were brought back to the Museum of the Rockies. Scannella said he and Horner tried for three years to look for alternative explanations for their findings. They finally agreed that the Triceratops and Torosaurus were the same dinosaur.

What is a group of T Rex called? ›

A "court of Tyrannosaurs" nice one! We had a similar suggestion a few months ago sent into us a "retinue of rexes". A clever geologist colleague explained at the time that a retinue was the name given to a group of attendants that travelled with an important person such as King.

What are the name of all dinosaurs? ›


Is the baby in dinosaurs a boy or girl? ›

Baby Sinclair

Earl and Fran's son and youngest child, he is a Megalosaurus as stated by Earl. In the episode "Out of the Frying Pan," Baby is shown as a Ceratosaurus.

Is dinosaurs a kid show? ›

That's right, a kid-friendly show about a family of dinosaurs ends with everyone freezing to death as the ice age is brought upon by none other than the dad, Earl Sinclair (voiced by Stuart Pankin).

How long did the dinosaurs live? ›

Dinosaurs went extinct about 65 million years ago (at the end of the Cretaceous Period), after living on Earth for about 165 million years.

Who is the biggest dinosaur? ›

Patagotitan mayorum, the Titanosaur

Patagotitan mayorum may have been the world's largest terrestrial animal of all time, based on size estimates made after considering a haul of fossilized bones attributed to the species. The collection included a femur (thighbone) that measured 2.4 meters (8 feet) from end to end.

What was the nicest dinosaur? ›

Friendliest Dinosaurs: Stegosaurus

The Stegosaurus is one of the friendliest dinosaurs to have ever been discovered. The Stegosaurus was a lizard-like, herbivorous dinosaur that lived in areas around the United States and Portugal between 155 and 150 million years ago.

How tall is the T Rex? ›

Do lizards have hips? ›

Seeley used the resemblance of dinosaur hips to those in other animals to name the two major groups. The hips of dinosaurs with forward-oriented pubic bones approximated the hips of lizards, so Seeley called them the saurischians (“lizard-hipped”).

How old are the earliest dinosaurs? ›

At 243 million years old, Nyasasaurus parringtoni may be the oldest known dinosaur. Sterling Nesbitt, a palaeontologist at the University of Washington in Seattle, and his colleagues describe the animal in a study published today in Biology Letters1.

When did the Jurassic period start and end? ›

What are any of the ornithischian dinosaurs? ›

There were many kinds of ornithischian dinosaurs, dating back to the early Jurassic. The Ornithopoda included the hadrosaurs ("duck-billed dinosaurs"), the iguanodontids, the heterodontosaurs, the hypsilophodontids, and various other dinosaurs.

How do you pronounce ornithischian? ›

How To Say Ornithischian - YouTube

What are the three main branches of ornithischian dinosaurs? ›

Ornithischians with well known anatomical adaptations include the ceratopsians or "horn-faced" dinosaurs (e.g. Triceratops), the pachycephalosaurs or "thick-headed" dinosaurs, the armored dinosaurs (Thyreophora) such as stegosaurs and ankylosaurs, and the ornithopods.

What was before dinosaurs? ›

For approximately 120 million years—from the Carboniferous to the middle Triassic periods—terrestrial life was dominated by the pelycosaurs, archosaurs, and therapsids (the so-called "mammal-like reptiles") that preceded the dinosaurs.

Did dinosaurs evolve fish? ›

As reviewed in a new paper in the Annual Review of Ecology, Evolution, and Systematics, about 398 million years ago there was a particular group of fish, the lobed-fined or sarcopterygian fish, the organisms that gave rise to our common ancestor with the dinosaurs.

When was the first dinosaur discovered? ›

In 1677, Robert Plot is credited with discovering the first dinosaur bone, but his best guess as to what it belonged to was a giant human. It wasn't until William Buckland, the first professor of geology at Oxford University, that a dinosaur fossil was correctly identified for what it was.

How were dinosaurs first created? ›

Dinosaurs are a type of reptile, and they evolved from another group of reptiles called 'dinosauromorphs' around 250 million years ago. The dinosauromorphs were small and humble animals, and they didn't look anything like T. rex or Brontosaurus.

What was the last dinosaur? ›

A Triceratops may have been the last dinosaur standing, according to a new study that determined a fossil from Montana's Hell Creek Formation is "the youngest dinosaur known to science."

What if dinosaurs were still alive? ›

It's likely that, with a preponderance of dinosaurs remaining on our planet, humans and many other mammals would not have had the chance to evolve into existence. “Even though mammals thrived in the shadow of the dinosaurs, they did so at small size,” writes Switek.

Why do humans have 2 legs? ›

Summary: A team of anthropologists that studied chimpanzees trained to use treadmills has gathered new evidence suggesting that our earliest apelike ancestors started walking on two legs because it required less energy than getting around on all fours.

What color was the first human? ›

These early humans probably had pale skin, much like humans' closest living relative, the chimpanzee, which is white under its fur. Around 1.2 million to 1.8 million years ago, early Homo sapiens evolved dark skin.

How old is human? ›

Modern humans originated in Africa within the past 200,000 years and evolved from their most likely recent common ancestor, Homo erectus. Modern humans (Homo sapiens), the species? that we are, means 'wise man' in Latin.

What did ornithischian dinosaurs evolve into? ›

The meat-eating theropods, which included the famous Tyrannosaurus rex, have evolved into the modern dinosaurs: birds. And the bird-hipped ornithischians, an assorted group of herbivorous dinosaurs, evolved some of the most bizarre anatomy known in evolutionary history.

How did birds evolve flying? ›

The cursorial hypothesis suggests that bird ancestors ran and jumped, perhaps to catch prey, and thus evolved flight as a way to enhance this, and to safely get back to the ground again.

How did the T. rex evolved into a chicken? ›

“A bird didn't just evolve from a T. rex overnight, but rather the classic features of birds evolved one by one; first bipedal locomotion, then feathers, then a wishbone, then more complex feathers that look like quill-pen feathers, then wings,” Brusatte said.

Did birds evolve from reptiles? ›

Dinosaurs and Birds

Although the living reptiles birds are most closely related to are crocodilians (archosaurs), when it comes to their relation to dinosaurs, birds evolved from theropod dinosaurs. These theropods share over 100 traits with modern birds.

How many dinosaurs are there? ›

At present over 700 different species of dinosaurs have been identified and named.

What are any of the ornithischian dinosaurs? ›

There were many kinds of ornithischian dinosaurs, dating back to the early Jurassic. The Ornithopoda included the hadrosaurs ("duck-billed dinosaurs"), the iguanodontids, the heterodontosaurs, the hypsilophodontids, and various other dinosaurs.

How do you pronounce ornithischian? ›

How To Say Ornithischian - YouTube

When did flight first evolve? ›

Insects were the first to evolve flight, approximately 350 million years ago. The developmental origin of the insect wing remains in dispute, as does the purpose prior to true flight.

What were the first animals to evolve flight? ›

Pterosaurs were the first vertebrate creatures to evolve powered flight and conquer the air—long before birds took wing. They prevailed for more than 160 million years before vanishing along with the nonbird dinosaurs at the end of the Cretaceous period, around 66 million years ago.

How many times did flying evolve? ›

Perhaps one of the most astonishing cases of convergent evolution is the origin of flight. Flight appears to have evolved separately four times in history: in insects, bats, birds and pterosaurs. These four groups of flying animals didn't evolve from a single, flying ancestor.

Is T. rex a chicken? ›

“We determined that T. rex, in fact, grouped with birds — ostrich and chicken — better than any other organism that we studied.

Did T. rex lay eggs? ›

rex parents cared for their young before or after they hatched. No T. rex eggs or nests have ever been found, but fossils of other Tyrannosaur relatives suggest that they laid elongated eggs, roughly 20 or more at a time.

Can a guinea mate with a chicken? ›

When confined together, chickens and guineas will interbreed on occasion, and sometimes the result is a fertile egg. Survival rate in these hybrids is higher if they are more like the guinea parent (in which case the incubation period is 25-26 days).

Are birds dinosaurs yes or no? ›

Birds belong to the theropod group of dinosaurs that included T. rex. Theropods are all bipedal and some of them share more bird-like features than others. Archaeopteryx, discovered in 1861, was for a long time the only truly bird-like dinosaur – it's from the Late Jurassic era (150 million years ago).

When did dinosaurs evolve? ›

Triassic Period (252 to 201 million years ago)

Unlike today, there were no polar ice caps. It was in this environment that the reptiles known as dinosaurs first evolved.

When did we discover birds are dinosaurs? ›

In the 1980s, cladistic methodology was applied to dinosaur phylogeny for the first time by Jacques Gauthier and others, showing unequivocally that birds were a derived group of theropod dinosaurs.


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