BIO 113 Dinosaurs
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Lab 11
Carnivorous Dinosaurs

Herrerasauridae


Herrerasauridae
  • Primitive Triassic dinosaurs: relationships under debate
  • Formerly considered part of Theropoda
  • May be sister group to Sauropodomorpha
  • Bipedal runner: long hind legs, short forelegs
  • Relatively small size
  • Squarish skull
  • Carnivorous
Herrerasaurus fossil
Herrerasaurus skeleton, Middle Triassic, Argentina (MAL1)
Herrerasaurus


Theropoda

  • Nearly all are bipedal: forelimbs shorter than hind limbs
  • Claws on all fingers and toes
  • Fairly long S-shaped necks
  • Relatively large head (most)
  • Hollow limb bones
  • Vertebrae with spaces for air sacs
  • 4 toes per hind foot (outer toe lost), with one toe often vestigial (does not reach ground)
  • 4 or fewer digits on fore limbs; one is usually somewhat opposable

Basal Theropods

  • Various primitive groups (paraphyletic grouping)
  • Typically have 4 fingers per hand (but one may be vestigial and not visible externally)
  • Small to medium-sized; slender build
  • Tail somewhat flexible

Coelophysidae
  • A primitive group of theropods
  • 4 fingers per hand (an ancestral trait)
  • Mostly small, with a slender build
  • Skull usually fairly elongated
  • Known primarily from Triassic Period
Coelophysis fossil
Coelophysis fossil, Late Triassic Period, New Mexico (WDC2)
Coelophysids

Dilophosauridae
  • 1 finger reduced (appear to have only 3)
  • Medium-sized, with moderately slender build
  • Thin bone crests on head
  • Known primarily from early Jurassic Period
Dilophosaurus fossil
Dilophosaurus fossil, Early Jurassic Period, Arizona
Dilophosaurids

Ceratosaurs

  • Relatively primitive, with four fingers (but one may be vestigial)
  • Morphologically diverse, with varied body sizes
  • Mostly in southern hemisphere

Ceratosauridae
  • 4 fingers per hand
  • Medium to large size
  • Fairly typical proportions for large predatory dinosaurs
  • Several small horns on head


Noasauridae
  • Small, slender dinosaurs
  • Relatively long, narrow skulls
  • Some with projecting teeth (for fish catching?)
Ceratosaurus fossil
Ceratosaurus skeleton, Late Jurassic Period, North America, Europe, Africa (MAL)
Ceratosaurs

Abelisauridae
  • Forelimbs greatly reduced, vestigial, but with 4 fingers
  • Medium to large size
  • Skulls are deep, and fairly short in derived forms
  • Crests and bumps on head or face are typical
Carnotaurus fossil
Carnotaurus skeleton, Late Cretaceous Period, Argentina (LAMNH3)
Abelisaurs

Tetanurans

  • All subsequent theropods belong to the clade Tetanurae
  • 3 Fingers (or fewer) per hand
  • Tail relatively stiff
  • Body size varies

"Carnosaurs"

  • Carnosaur was a name applied to most large predatory dinosaurs
  • Phylogenetic analysis indicates Carnosaurs are not monophyletic, so the name is falling out of use
  • Large size with fairly typical shapes for large predatory dinosaurs
  • For convenience, and since there are few external differences, we will combine most typical large carnivores, such as the Allosauroids and Megalosaurs, into a general "Carnosaur" grouping in lab

Megalosauridae
  • Megalosaurs are medium to large generalized theropods
  • Few obvious specializations; lack crests or horns on head
  • Large claw on thumb
  • Includes Megalosaurus, the first named dinosaur
  • Formerly included with other large theropods in the "Carnosauria"
Torvosaurus fossil
Torvosaurus skeleton, Late Jurassic Period, North America (MAL)
Megalosaurs

Spinosauridae
  • Large to very large size
  • Long, narrow snout with enlarged tip
  • Small centrally-located crest on forehead
  • Teeth conical, without serrations
  • Most likely were piscivorous (fish eaters); some where semi-aquatic (the only known aquatic dinosaurs)
Suchomimus fossil
Suchomimus skull, Early Cretaceous Period, Africa (MAL)
Spinosaurs

Allosauroids
  • A large, diverse group of generalized predators
  • Mostly large to very large size
  • Generally have somewhat elongated skulls with large orbits
  • Many have ridge or horn above eye (but not unique to this group)
Giganotosaurus fossil
Giganotosaurus skeleton, Late Cretaceous Period, Argentina (FMNH4)
Allosauroids

Megaraptors
  • May be related to Allosauroids or Tyrannosauroids?
  • Enlarged thumb claw
  • Mostly medium-sized
Megaraptors

Theropods of Uncertain Relationships
  • Relationships uncertain
  • Not closely related to any major group (or each other)
  • They will be treated as generic "Carnosaurs"
Monolophosaurus fossil
Monolophosaurus skeleton, Late Cretaceous Period, Argentina (WDC)
Miscellaneous Theropods

Coelurosauria

  • All subsequent tetanuran theropods belong to the clade Coelurosauria
  • Enlarged sacrum (the vertebrae between the pelvic bones)
  • Stiffened tail
  • Tibia (lower leg) longer than femur (upper leg)
  • Perhaps all had some sort of feathers or protofeathers
  • Ancestrally small-sized, and most were small-medium sized, but a few did evolve very large sizes

Tyrannosauroidea
  • All have relatively blunt snout
  • United by various subtle skeletal characteristics
  • Primitive forms were relatively small, resembled other coelurosaurs
  • Some primitive forms known to have simple protofeathers
  • Derived Tyrannosaurids distinctive:
    • Large size
    • Proportionately large head
    • Greatly reduced arms with only 2 fingers
Tyrannosaurus fossil
Tyrannosaurus skeleton, Late Cretaceous Period, North America (MAL)
Primitive Tyrannosaurs
Primitive Tyrannosaurs

Compsognathidae
  • Compsognathids were small, agile dinosaurs
  • Proportionately long tails
  • At least some (or all?) had simple proto-feathers
Compsognathus fossil
Compsognathus skeleton, Late Jurassic Period, Europe (MAL)
Compsognathids

Ornithomimosauria
  • Ostrich Dinosaurs
  • Slender build, with long legs, long slender necks
  • Small heads that were toothless in most (or with tiny peg-like teeth)
  • Gastroliths present; probably herbivorous or omnivorous
  • One species known to have feathers
Struthiomimus fossil
Struthiomimus skeleton, Late Cretaceous Period, North America (MAL)
Ornithomimids

Alvarezsauridae
  • Small, with long legs and neck
  • Small heads with tubular snout
  • Very short but powerful arms
  • Single, massive claw on each hand
  • Loose, filamentous feathers known from one species
  • May have been termite specialists

Therizinosauroidea
  • Very unusually shaped theropods
  • Size varies from small to large
  • Body broad and heavy, with wide hips and short tail
  • Long necks with small heads
  • Very long arms with enormous claws
  • Probably herbivorous
  • Loose, filamentous feathers known from one species
Nothronychus fossil
Nothronychus skeleton, Late Cretaceous Period, Southwestern USA (AZMNH5)
Therizinosaurs

Oviraptorosauria
  • Long arms and short tails distinctive
  • Most were small (but at least one large species)
  • Very short skulls with (usually) toothless, parrot-like beak
  • Some had prominent crests on their heads
  • Feathers with flat vanes that may have functioned in display
  • Diet uncertain: evidence for both herbivory and carnivory
Oviraptor fossil
Oviraptor skeleton, Late Cretaceous Period, China
Oviraptors

Scansoriopterygidae
  • Greatly elongated 3rd finger
  • Finger and modified wrist bone support membranous wing
  • Blunt, downcurved snout with large front teeth
  • Unique ribbon-like tail feathers
  • All 3 species small
  • Probably tree climbers and gliders
Scansoriopterygids

Dromeosauridae
  • Commonly referred to as "raptors"
  • Very small to medium size
  • Agile, with fairly long arms, long fingers
  • Inner hind toe with a greatly enlarged, retractible slashing claw
  • Skulls elongated
  • Tails long and stiff
  • Well developed feathers with vanes
  • Some capable of gliding flight
Velociraptor fossil
Velociraptor skeleton, Late Cretaceous Period, Asia (WDC)
Dromeosaurs

Troodontidae
  • Similar to the Dromeosaurs, but with smaller slashing claw
  • Mostly small sized
  • Smaller heads than Dromeosaurs with distinctive teeth
  • Relatively large-brained
  • Well developed feathers with vanes
  • May not form a monophyletic group
  • Probably the sister group to the birds (Class Aves)
Troodontids

Footnotes
  1. MAL = Museum of Ancient Life, Lehi, UT
  2. WDC = Wyoming Dinosaur Center, Thermopolis
  3. LAMNH = Los Angeles Museum of Natural History
  4. FMNH = Fernbank Museum of Natural History, GA
  5. AZMNH = Arizona Museum of Natural History, Mesa
This page last updated 14 July 2017 by Udo M. Savalli ()
Images and text Udo M. Savalli. All rights reserved.