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GEOL 240 The Dinosaurs: Sauropods. Sauropodomorphs.

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Presentation on theme: "GEOL 240 The Dinosaurs: Sauropods. Sauropodomorphs."— Presentation transcript:

1 GEOL 240 The Dinosaurs: Sauropods

2 Sauropodomorphs

3 Saurischia ("lizard-hipped" or "reptile- hipped") Ornithischia ("bird-hipped")

4 Sauropodomorphs z Name means "sauropod form"; Sauropoda means "lizard feet", even though their feet do not look much like lizard feet!  Characterized by: yEnlarged nares yAn elongated neck yLeaf-shaped teeth  Herbivores  “Primitive” forms are facultative bipeds; later forms were so large they were obligate quadrupeds  Were the largest herbivores ever to live on land; by the end of the Upper Triassic fossil forms had surpassed all previous land living animals in size, and kept on going…

5 Sauropodomorphs zUnique Characteristics yheads that were very small compared to body yspatulate teeth yat least 10 elongated vertebrae in the neck yshort feet yvery large claws on the I digit of the forefoot

6 Sauropodomorphs

7 Composed of two groups: Sauropods & Prosauropods

8 Probably not the sharpest knives in the drawer

9 Prosauropods zone of the first classes of plant-eating dinosaurs zRange from Upper Triassic to Lower Jurassic z Evolutionary speculation on whether they form a paraphyletic grade leading to the Sauropoda; form their own monophyletic group Prosauropoda; or a combination of both. zGenerally thought of as closest relatives but not direct ancestors of sauropods zWhy the question? There is nothing “primitive” about them to suggest they were an ancestral grade.

10 Prosauropods Unique characteristics First fossils small size (1.5-2 m long), but eventually reaching 10 m or more First fossil forms appear to have been obligate bipeds, (how could we tell that?) but as size increases they appear to become facultative bipeds A big thumb claw and grasping hands Some prosauropods may have had a beak, although this is uncertain

11 Prosauropods Unique characteristics cont. Simple leaf-shaped teeth with no occlusion Only two or three sacrals: lower than almost all other dinosaur groups (9-11 in Edmontosarurus and Triceratops resp.) Prosauropods were the most common herbivorous dinosaurs from the Upper Triassic to the Lower Jurassic; no prosauropod fossils above the Middle Jurassic – i.e. none on the Ranch

12 z Prosauropods were the first large- bodied dinosaur fossil group. Their long necks would allow them to browse higher in trees than any contemporaneous herbivores. Also, larger size would give them bigger guts to digest more plants and defense against predators. Prosauropods

13 Long neck, long tail, saurischian pelvis Plateosaurus, based on Galton (1990). fairly large (about 6-8 m long) Prosauropods

14

15 Jaw joint below the tooth row Prosauropods

16 Claw from digit I Prosauropods

17 zhave a body plan like a biped, but the trackways suggest that they usually walked quadrupedally zforelimbs were at least two-thirds the length of the hind limbs zdigit I of the hand was much larger than the others and bore a large claw zcould conceivably have reared up on hind limbs to reach vegetation higher in trees Prosauropods

18 zHerbivores ylong necks to extend vertical feeding range yhad cheeks - allows food to be retained while chewed (How could you know that?) yjaw hinge below tooth line ytooth rows almost parallel yspatulate teeth - resemble teeth of modern Iguana - a plant eating lizard ydiscovery of gastroliths - gastric stones for grinding Prosauropods

19 Mussaurus z“mouse-lizard” z~20 cm long probably a baby zsuggests Prosauropods laid eggs

20 Sauropods z Include the largest land animals of all time z The oldest known sauropod is from the end of the Late Triassic, but sauropods do not become common until the Middle Jurassic.

21 zImportant Features Extremely large size: all sauropods were at least elephant-sized as adults, and many much, much larger Obligate quadrupedality Reduced skull size Nares placed at least as high dorsally as the orbits Tooth-to-tooth occlusion for precise bites Extra cervical vertebrae Four or more sacrals Reduced number of phalanges on manus Long necks and tails Sauropods

22 Sauropods

23 Lateral temporal opening partially below orbit Sauropods

24 Sauropods

25 Sauropods

26 Diplodocidae zskulls were long and slender with elongate muzzles zthe jaws bore peg-like teeth confined to the front of the mouth znostrils were on top of the skull in front and above the orbits Diplodocus Apatosaurus Dicraeosaurus

27 Diplodocus zBodies were long and relatively lightly built (including the longest, but not heaviest) znecks were extremely long with an increased number of vertebrae zfewer vertebrae in the back

28 Diplodocoids: zPencil-shaped teeth only at very end of snout zNares are placed together above the orbits zTails ended in very narrow and long caudals z Forelimbs much shorter than hindlimbs

29 Apatosaurus zIts more familiar name is Brontosaurus, although that name was given after the name Apatosaurus was applied. zApatosaurus was shorter but stockier than Diplodocus. For a long time the wrong head was associated with Apatosaurus. A Camarasaurus-like skull was made up and put on the Apatosaurus skeleton, which otherwise lacked a head. It turns out that a good candidate skull was found in the same quarry as Apatosaurus and fits the skeleton much better. It is a rather typical diplodocid skull, although distinctly different to Diplodocus itself.

30 Apatosaurus

31 His two skulls Apatosaurus

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33 Camarasauridae zShort heavy skull with a blunt snout zlarge, spoon-shaped (spatulate) teeth along the entire length of the mouth zlarge nostrils located on the sides of the skull just in front of the eyes zsolidly built body, neither overly long nor overly heavy zonly 12 neck vertebrae

34 Camarasaurid limbs were stout with humerus to femur ratios of around 0.7 or more - relatively longer than in Diplodocids The wrist and ankle each had two bones Camarasauridae

35 Brachiosaurids zProbably the heaviest land animals to ever live zSkull and teeth resemble those of Camarasaurus zforelimb was long with humerus to femur ratios of greater than 1.0 zShoulders were higher than hips

36 Brachiosaurids

37 Brachiosaurids z13 neck vertebrae - very elongated z dorsal vertebrate z50 vertebrate in tail - individually short so the tail is not that long

38 Cetiosaurids zrelatively small sauropods - 12 meters long zskull similar to camarasaurids with longer muzzle znumerous, slender teeth - small spoon- shaped crowns z12 cervical vertebrae z13 dorsal vertebrae zhumerus-to-femur ratio about 0.66

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40 Titanosauridae zlarge number of vertebrae in sacrum (6) zone titanosaurid had body armor


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