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Dinosaur Classification Facts & Worksheets

Dinosaurs are a diverse group of reptiles that once dominated the Earth. They belong to the larger group Archosauria, which also includes crocodiles and birds. The classification of dinosaurs is typically based on various factors, including their skeletal features, such as the structure of the hip, skull, and limbs.

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Dinosaurs are a diverse group of reptiles that once dominated the Earth. They belong to the larger group Archosauria, which also includes crocodiles and birds. The classification of dinosaurs is typically based on various factors, including their skeletal features, such as the structure of the hip, skull, and limbs.

See the fact file below for more information about Dinosaur Classification, or you can download our 32-page Dinosaur Classification worksheet pack to utilize within the classroom or home environment.

Key Facts & Information

DINOSAUR TIMELINE

  • The dinosaur timeline spans a vast expanse of Earth’s history, covering millions of years from the Triassic period to the end of the Cretaceous period. 
  • Dinosaurs emerged during the Late Triassic, around 230 million years ago, and their reign persisted until the Cretaceous-Paleogene (K-Pg) extinction event about 65 million years ago. 
  • This timeline provides a glimpse into the major periods and significant developments in the fascinating history of dinosaurs.
  • Triassic Period (230 to 201 million years ago):
    • Dinosaurs first appeared in the Late Triassic, evolving from earlier archosaurs. Among the early dinosaurs were small, bipedal forms like Eoraptor and Herrerasaurus.
    • The Triassic saw the dominance of the Archosaurs, which included not only dinosaurs but also their close relatives, such as crocodiles.
  • Jurassic Period (201 to 145 million years ago):
    • The Jurassic is often referred to as the “Age of Dinosaurs.” Dinosaurs diversified and became more widespread during this period.
    • Iconic dinosaurs such as the long-necked Brachiosaurus, the armored Stegosaurus, and the formidable Allosaurus thrived during the Jurassic. The first birds, like Archaeopteryx, also appeared during this time.
  • Cretaceous Period (145 to 66 million years ago):
    • The Cretaceous period witnessed the further evolution and diversification of dinosaurs. It is known for the dominance of the enormous herbivorous Sauropods and the appearance of advanced theropods like Tyrannosaurus rex.
    • The continents were still shifting, leading to the separation of landmasses and the development of distinct ecosystems.
  • Late Cretaceous (99 to 66 million years ago):
    • The Late Cretaceous was marked by diverse dinosaur species, including the ceratopsians like Triceratops and the duck-billed Hadrosaurs.
  • The oceans were inhabited by marine reptiles like Ichthyosaurs and Plesiosaurs.
  • K-Pg Extinction Event (66 million years ago):
    • The Cretaceous-Paleogene extinction event, also known as the K-Pg event, marked the end of the Mesozoic Era and the supremacy of the dinosaurs.
    • This catastrophic event led to the extinction of approximately 75% of Earth’s species, including all non-avian dinosaurs. The exact cause is debatable, but a widely accepted theory involves a massive asteroid impact.
  • Post-Dinosaur Era (66 million years ago to Present):
    • Following the extinction of dinosaurs, mammals, including early primates, began to diversify and fill ecological niches left vacant by the dinosaurs.
  • Birds, considered avian dinosaurs, survived the mass extinction and continued to evolve. They eventually gave rise to the diverse bird species we see today.
  • The dinosaur timeline is a captivating journey through Earth’s ancient past, showcasing the rise, dominance, and eventual decline of these remarkable creatures. 
  • Fossil discoveries and ongoing research continually enhance our understanding of this prehistoric era, unraveling mysteries and shedding light on the intricate web of life that existed millions of years ago.

DINOSAUR CLASSIFICATION – SAURISCHIA

  • The name “Saurischia” is derived from the Greek words “sauros,” meaning lizard, and “ischion,” meaning hip. The defining characteristic distinguishing Saurischian dinosaurs is the structure of their hip bones. 
  • The hip structure of Saurischians is similar to that of modern reptiles, with a pubis bone pointing forward and a long, slender ischium pointing backward. This configuration is often referred to as a “lizard-hip.”
  • Saurischia is divided into two major subgroups based on additional anatomical features and evolutionary relationships:
  • Theropoda:
    • Theropods are a diverse group of bipedal, mainly carnivorous dinosaurs. They played a crucial role in the Mesozoic ecosystems as apex predators. 
    • Some theropods, such as birds, survived the mass extinction event at the end of the Cretaceous period and continue to thrive today.
    • Notable theropods include the fearsome Tyrannosaurus rex, the agile Velociraptor, and the bird-like Archaeopteryx, considered a transitional form between non-avian dinosaurs and birds.
  • To summarize Theropoda:
    • Characteristics: Bipedal locomotion, typically carnivorous, with a distinct predatory lifestyle.
    • Examples: Tyrannosaurus rex, Velociraptor, Allosaurus, and modern birds.
  • Sauropodomorpha:
    • Sauropodomorphs, on the other hand, were primarily herbivorous dinosaurs characterized by their long necks, small heads, and massive bodies. They were the largest land animals to have ever existed.
  • Sauropods, like Brachiosaurus and Apatosaurus, were part of this group. These dinosaurs were adapted to a herbivorous diet, likely consuming vast amounts of plant material to sustain their enormous size.
  • To summarize Sauropodomorpha:
    • Characteristics: Typically herbivorous, with long necks and tails, quadrupedal or semi-bipedal locomotion.
    • Examples: Brachiosaurus, Apatosaurus, Diplodocus, and other long-necked sauropods.
  • It’s important to note that Saurischia as a whole includes the ancestors of birds, and thus, birds are considered a subgroup of theropod dinosaurs within the Saurischian clade. 
  • The classification of dinosaurs is dynamic, with ongoing research and new discoveries contributing to our understanding of their evolutionary relationships and diversity.

DINOSAUR CLASSIFICATION – ORNITHISCHIA

  • The name “Ornithischia” is derived from the Greek words “ornis,” meaning bird, and “ischion,” meaning hip. Unlike the lizard-hipped Saurischians, Ornithischian dinosaurs have a hip structure that is superficially similar to that of modern birds.
  • Ornithischians are characterized by a hip structure in which the pubis bone points backward and the ischium bone points forward, creating a structure known as a “bird-hip.”
  • Ornithischia is divided into several subgroups, each with its own unique characteristics and representative species. Some notable examples of Ornithischian dinosaurs include:
  • Marginocephalia: The Shield-Head Dinosaurs
    • Marginocephalia is a group of dinosaurs that share a unique feature: a bony structure at the back of their heads, often in the form of frills or domes.
  • Thyreophora: The Armored Dinosaurs
    • Thyreophora is a group of dinosaurs known for their armored bodies, which helped protect them from predators. Scientists believe that Stegosaurus’ plates might have been used to regulate body temperature, acting like a sort of “solar panel” for absorbing or releasing heat.
  • Ornithopoda: The Beaked Dinosaurs
    • Ornithopoda is a group of dinosaurs known for their bird-like hips and beak-shaped mouths. They were herbivores. Their beak-shaped mouths were adapted for efficiently cropping vegetation.
  • Ceratopsia: The Horned and Frilled Dinosaurs
    • Ceratopsia is a group of dinosaurs known for their distinctive horns and frills on their heads. Different ceratopsian species had varying horn and frill arrangements. 
    • Some had long frills with intricate patterns of spikes, while others had shorter frills with heftier horns. They were also herbivores.

THE SURVIVORS

  • Were there survivors of the dinosaurs? Yes, there are survivors of the dinosaurs that fall into these classifications. The most notable survivors are birds, which are considered the living descendants of theropod dinosaurs. 
  • The classification Saurischia includes Theropoda, a group of bipedal, mainly carnivorous dinosaurs, and birds are considered a subgroup of theropods. Therefore, birds are, in essence, modern-day dinosaurs.

Dinosaur Classification Worksheets

This fantastic bundle includes everything you need to know about Dinosaur Classification across 32 in-depth pages. These ready-to-use worksheets are perfect for teaching kids about Dinosaur Classification. The classification of dinosaurs is typically based on various factors, including their skeletal features, such as the structure of the hip, skull, and limbs.

Complete List of Included Worksheets

Below is a list of all the worksheets included in this document.

  1. Dinosaur Classification Facts
  2. Quick Review
  3. Dinosaur Impressions
  4. Therophod Jumble
  5. Gigantic Pictures
  6. Shield-Headed Dino
  7. Armored Dinosaurs
  8. Beaked Dinosaurs
  9. Horned and Frilled Dinosaurs
  10. Latest Discoveries
  11. Think About It!

Frequently Asked Questions

What are the main groups into which dinosaurs are classified?

Dinosaurs are classified into two main groups: the Saurischia and Ornithischia. Saurischia includes theropods (bipedal, carnivorous dinosaurs) and sauropodomorphs (mostly herbivorous, long-necked dinosaurs). Ornithischia comprises herbivorous dinosaurs with a bird-like hip structure.

How do paleontologists determine the classification of a dinosaur species?

Paleontologists use various anatomical features, especially those of the hip structure, skull, teeth, and limb bones, to classify dinosaurs. The arrangement of these features helps determine whether a dinosaur belongs to the Saurischia or Ornithischia group and provides insights into its specific subgroup.

What is the significance of the terms “theropod” and “sauropod” in dinosaur classification?

“Theropod” refers to a subgroup of saurischian dinosaurs characterized by bipedal stance and typically carnivorous habits. “Sauropod” refers to another saurischian subgroup known for their long necks, small heads, and massive bodies, with most being herbivorous. Both terms help in more specific categorization within the broader classification.

Are there any transitional forms or “missing links” in dinosaur classification?

Some dinosaurs exhibit characteristics of both Saurischia and Ornithischia, leading to discussions about transitional forms. One example is the Herrerasaurus, which shows features of both groups. While the term “missing link” may be misleading, these transitional forms provide valuable insights into the evolutionary history of dinosaurs.

How do scientists determine the diet of a dinosaur based on its classification?

The shape and structure of a dinosaur’s teeth, along with other features like jaw mechanics and digestive system adaptations, provide clues about its diet. For example, sharp, serrated teeth are often indicative of a carnivorous diet, while flat, grinding teeth suggest herbivorous habits. This dietary information helps in refining the classification and understanding the ecological roles of different dinosaur species.

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