Dinosaur Overview and Diversity

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Questions and Answers

During which period did dinosaurs first appear?

Jurassic

Paleogene

Cretaceous

Triassic (correct)

What major event allowed dinosaurs to become dominant terrestrial vertebrates?

Cretaceous–Paleogene extinction event

Ordovician extinction event

Triassic–Jurassic extinction event (correct)

Permian mass extinction

What group do birds belong to within dinosaurs?

Reptilian dinosaurs

Extinct dinosaurs

Avian dinosaurs (correct)

Non-avian dinosaurs

What misconception about dinosaurs was prevalent before the 1970s?

Dinosaurs were sluggish and cold-blooded. Signup and view all the answers

How many distinct genera of non-avian dinosaurs have paleontologists identified using fossil evidence?

Over 900 Signup and view all the answers

What adaptation is common among many dinosaur species in relation to their reproduction?

All dinosaurs were egg-laying. Signup and view all the answers

Which feature was NOT common among all dinosaur groups?

Bipedal stance Signup and view all the answers

What characteristic is a typical feature of the largest sauropod dinosaurs?

They were the largest land animals of all time. Signup and view all the answers

What is a major reason for the misconception that all non-avian dinosaurs were large?

Larger bones are more likely to preserve as fossils. Signup and view all the answers

Who coined the term 'dinosaur'?

Richard Owen Signup and view all the answers

What type of dinosaur includes both herbivorous and carnivorous species?

Saurischia Signup and view all the answers

Which group of dinosaurs is defined as containing the last common ancestor of Triceratops and modern birds?

Dinosauria Signup and view all the answers

What recent finding by researchers suggested a change in traditional dinosaur systematics?

Ornithischia are closer to Theropoda than Sauropodomorpha. Signup and view all the answers

Which of the following groups does NOT belong to Dinosauria?

Mammals Signup and view all the answers

What definition did Baron et al. propose to include sauropods within dinosaurs?

The last common ancestor of Triceratops, Passer, and Diplodocus Signup and view all the answers

Which feature distinguishes Maniraptora within dinosaur classifications?

They are synchronized with bird evolution. Signup and view all the answers

What is the primary reason for the public's ongoing interest and investment in dinosaur science?

New discoveries are constantly made and promoted in media. Signup and view all the answers

Which of the following characteristics pertains to Theropoda?

They primarily include bipedal carnivores. Signup and view all the answers

Study Notes

Dinosaur Overview

Dinosaurs are a diverse group of reptiles from the clade Dinosauria.
Their existence began during the Triassic period (243-233.23 million years ago). Ongoing research explores their exact origin and evolutionary timing.
Dinosaurs became dominant terrestrial vertebrates post-Triassic–Jurassic extinction (201.3 million years ago).
Birds are feathered dinosaurs, evolving from earlier theropods in the Late Jurassic and are the sole surviving dinosaur lineage.
Dinosaurs are categorized into avian (birds) and extinct non-avian dinosaurs.

Dinosaur Diversity

Dinosaurs display wide variety taxonomically, morphologically, and ecologically.
Bird diversity stands out, with over 11,000 living species, representing a significant portion of vertebrate diversity.
Paleontological evidence suggests over 900 genera and 1,000 species of non-avian dinosaurs.
Dinosaur fossils are found on every continent, showcasing their global distribution.
Historically, dinosaurs were perceived as sluggish and cold-blooded; however, modern research suggests they were active with elevated metabolisms and complex social behaviours.
Dinosaur diets varied, with herbivorous and carnivorous species.
All dinosaurs were egg-laying, and many built nests, a shared characteristic between avian and non-avian dinosaurs.

Dinosaur Morphology and Size

Dinosaurs exhibited bipedal locomotion, although many extinct species were quadrupedal, with some capable of switching between stances.
Common display features include horns and crests. Some groups evolved skeletal enhancements like bony armor and spines.
Modern birds (avian dinosaurs) are generally smaller due to flight adaptation constraints.
However, many prehistoric dinosaurs (avian and non-avian) were large-bodied, including the estimated 39.7-meter (130 ft) sauropods, the largest land animals ever.
The misconception of uniform dinosaur gigantism is due to a preservation bias: large, robust bones are more likely to fossilize.

Dinosaur Discovery and Cultural Impact

Dinosaur fossils were recognized in the early 19th century.
The term "dinosaur," meaning "terrible lizard," was coined by Sir Richard Owen in 1842.
Dinosaur skeletons are common museum exhibits.
Dinosaurs have a prominent role in popular culture, especially through films like Jurassic Park.
Public interest generates funding for further dinosaur research and contributes to media coverage of new discoveries.

Phylogenetic Definition and Classification

Dinosaurs are defined phylogenetically as the group including the most recent common ancestor (MRCA) of Triceratops and modern birds, and all its descendants.
Alternative definitions use the MRCA of Megalosaurus and Iguanodon.
Dinosauria encompasses Ornithischia (e.g., ankylosaurians, stegosaurians, ceratopsians, pachycephalosaurians, ornithopods) and Saurischia (e.g., theropods, sauropodomorphs).
Birds are the only surviving lineage of dinosaurs.
Previously, birds were separated as a distinct class, but contemporary paleontology classifies them within the Dinosauria according to phylogenetic relationships.
Birds belong to the dinosaur group Maniraptora (coelurosaurs, theropods, saurischians).
Research from 2017 proposed a revision of dinosaurian systematics, suggesting Ornithischia is more closely related to Theropoda than Sauropodomorpha.
This revised definition included sauropods and their relatives as dinosaurs in the clade, with a new clade, Ornithoscelida, suggested to encompass Ornithischia and Theropoda.

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Description

Explore the fascinating world of dinosaurs, from their origins in the Triassic period to their evolution and diversity. Learn about the classification of dinosaurs into avian and non-avian types, and discover the significant diversity that exists among bird species today, as well as the fossil records of non-avian dinosaurs found worldwide.