Old Earth Ministries Online Earth History Curriculum

Presented by Old Earth Ministries (We Believe in an Old Earth...and God!)

This curriculum is presented free of charge for use by homeschooling families.

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Chapter 9, The Triassic Period

Lesson 48: Dinosaurs


     Dinosaurs are a diverse group of reptiles. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period (about 230 million years ago) until the end of the Cretaceous period (about 65 million years ago), when the Cretaceous–Tertiary extinction event caused the extinction of most dinosaur species, except for some birds. Evolutionists believe the fossil record indicates that birds evolved from theropod dinosaurs during the Jurassic period, and most paleontologists regard them as the only group of dinosaurs to have survived until the present day.

     This lesson will give a short introduction of dinosaurs, and a brief discussion on their importance in the creation science debate.  Please note that scientists interpret dinosaurs within an evolutionary framework, and the majority of scientists believe birds evolved from dinosaurs.  The discussion below includes these evolutionary beliefs.

Chapter 9 - The Triassic Period


 Lesson 44 - Triassic Overview

 Lesson 45 - The Tethys Ocean

 Lesson 46 - Supercontinent Pangea

 Lesson 47 - Triassic Species In-Depth, Ichthyosaur

 Lesson 48 - Dinosaurs



ABOVE:  Mounted skeletons of Tyrannosaurus (left) and Apatosaurus (right) at the American Museum of Natural History  (Picture Source

     Dinosaurs that existed prior to their supposed transition into birds are called "non-avian" dinosaurs. Paleontologists have identified over 500 distinct genera and more than 1,000 different species of non-avian dinosaurs. Dinosaurs are represented on every continent by both extant species and fossil remains. Some dinosaurs are or were herbivorous, others carnivorous. Some have been bipedal, others quadrupedal, and others have been able to shift between these body postures. Many non-avian species developed elaborate skeletal modifications such as bony armor, horns or crests. Although generally known for the large size of some species, most dinosaurs were human-sized or even smaller. Most groups of dinosaurs are known to have built nests and laid eggs.

     The term "dinosaur" was coined in 1842 by the English paleontologist Richard Owen, and derives from Greek δεινός (deinos) "terrible, powerful, wondrous" + σαῦρος (sauros) "lizard". Through the first half of the twentieth century, most of the scientific community mistakenly believed dinosaurs to have been sluggish, unintelligent cold-blooded animals. Most research conducted since the 1970s, however, has indicated that dinosaurs were active animals with elevated metabolisms and numerous adaptations for social interaction.

Since the first dinosaur fossils were recognized in the early nineteenth century, mounted dinosaur skeletons have been major attractions at museums around the world, and dinosaurs have become a part of world culture. They have been featured in best-selling books and films such as Jurassic Park, and new discoveries are regularly covered by the media. The outdated image of dinosaurs as maladapted extinct monsters has led to the word "dinosaur" entering the vernacular to describe anything that is impractically large, slow-moving, obsolete, or bound for extinction.


General Description


      Dinosaurs (aside from birds) can be generally described as terrestrial archosaurian reptiles with limbs held erect beneath the body, that existed from the Late Triassic (first appearing in the Carnian faunal stage) to the Late Cretaceous (going extinct at the end of the Maastrichtian). Many prehistoric animals are popularly conceived of as dinosaurs, such as ichthyosaurs, mosasaurs, plesiosaurs, pterosaurs, and Dimetrodon, but are not classified scientifically as dinosaurs. Marine reptiles like ichthyosaurs, mosasaurs, and plesiosaurs were neither terrestrial nor archosaurs; pterosaurs were archosaurs but not terrestrial; and Dimetrodon was a Permian animal more closely related to mammals.

     Dinosaurs were the dominant terrestrial vertebrates of the Mesozoic, especially the Jurassic and Cretaceous. Other groups of animals were restricted in size and niches; mammals, for example, rarely exceeded the size of a cat, and were generally rodent-sized carnivores of small prey.

     Dinosaurs were an extremely varied group of animals; according to a 2006 study, over 500 dinosaur genera have been identified with certainty so far, and the total number of genera preserved in the fossil record has been estimated at around 1850, nearly 75% of which remain to be discovered.  As of September 17, 2008, 1047 different species of dinosaurs have been named. Some were herbivorous, others carnivorous. Some dinosaurs were bipeds, some were quadrupeds, and others, such as Ammosaurus and Iguanodon, could walk just as easily on two or four legs.   Dinosaur remains have been found on every continent on Earth, including Antarctica. No dinosaurs are known to have lived in marine or aerial habitats, although it is possible some feathered theropods were flyers. There is also evidence that some spinosaurids had semi-aquatic habits.




     While the evidence is incomplete, it is clear that, as a group, dinosaurs were large. Even by dinosaur standards, the sauropods were gigantic. For much of the dinosaur era, the smallest sauropods were larger than anything else in their habitat, and the largest were an
Dinosaur scale
Scale diagram comparing the largest known dinosaurs in five major clades and a human (Click Picture for Larger View (Picture Source)
 order of magnitude more massive than anything else that has since walked the Earth. Giant prehistoric mammals such as the Indricotherium and the Columbian mammoth were dwarfed by the giant sauropods, and only a handful of modern aquatic animals approach or surpass them in size – most notably the blue whale, which reaches up to 173,000 kg (381,000 lb) and over 30 meters (100 ft) in length. There are several proposed advantages for the large size of sauropods, including protection from predation, reduction of energy use, and longevity, but it may be that the most important advantage was dietary. Large animals are more efficient at digestion than small animals, because food spends more time in their digestive systems. This also permits them to subsist on food with lower nutritive value than smaller animals. Sauropod remains are mostly found in rock formations interpreted as dry or seasonally dry, and the ability to eat large quantities of low-nutrient browse would have been advantageous in such environments.

      Most dinosaurs, however, were much smaller than the giant sauropods. Current evidence suggests that dinosaur average size varied throughout the time of their existance.   Theropod dinosaurs, when sorted by estimated weight into categories based on order of magnitude, most often fall into the 100 to 1000 kilogram (220 to 2200 lb) category, whereas recent predatory carnivorans peak in the 10 to 100 kilogram (22 to 220 lb) category. The mode of dinosaur body masses is between one and ten metric tonnes. This contrasts sharply with the size of Cenozoic mammals, estimated by the National Museum of Natural History as about 2 to 5 kilograms (5 to 10 lb).


Largest and Smallest


     The tallest and heaviest dinosaur known from good skeletons is Giraffatitan brancai (previously classified as a species of Brachiosaurus). Its remains were discovered in Tanzania between 1907–12. Bones from multiple similar-sized individuals were incorporated into the skeleton now mounted and on display at the Humboldt Museum of Berlin; this mount is 12 meters (39 ft) tall and 22.5 meters (74 ft) long, and would have belonged to an animal that weighed between 30,000 and 60,000 kilograms (70,000 and 130,000 lbs). The longest complete dinosaur is the 27-meter (89 ft) long Diplodocus, which was discovered in Wyoming in the United States and displayed in Pittsburgh's Carnegie Natural History Museum in 1907.

      There were larger dinosaurs, but knowledge of them is based entirely on a small number of fragmentary fossils. Most of the largest herbivorous specimens on record were all discovered in the 1970s or later, and include the massive Argentinosaurus, which may have weighed 80,000 to 100,000 kilograms (90 to 110 short tons); some of the longest were the 33.5 meters (110 ft) long Diplodocus hallorum (formerly Seismosaurus) and the 33 meters (110 ft) long Supersaurus; and the tallest, the 18 meters (59 ft) tall Sauroposeidon, which could have reached a sixth-floor window. The longest of them all may have been Amphicoelias fragillimus, known only from a now lost partial vertebral neural arch described in 1878. Extrapolating from the illustration of this bone, the animal may have been 58 meters (190 ft) long and weighed over 120,000 kg (260,000 lb). The largest known carnivorous dinosaur was Spinosaurus, reaching a length of 16 to 18 meters (50 to 60 ft), and weighing in at 8150 kg (18,000 lb).  Other large meat-eaters included Giganotosaurus, Carcharodontosaurus and Tyrannosaurus.
The theropod Anchiornis in a scale drawing with a human (Picture Source)

     Not including modern birds, the smallest dinosaurs known were about the size of a pigeon. The theropods Anchiornis and Epidexipteryx both had a total skeletal length of under 35 centimeters (1.1 ft). Anchiornis is currently the smallest dinosaur described from an adult specimen, with an estimated weight of 110 grams. The smallest herbivorous dinosaurs included Microceratus and Wannanosaurus, at about 60 cm (2 ft) long each


Creation Science and Dinosaurs (Optional)

     Dinosaurs are very popular with young earth creationists.  This is because they are extinct, and they view their extinction as a direct result of their belief in a global flood as told in the story of Noah.  As old earth creationists, we believe that the flood of Noah was a local event, and that dinosaurs died 65 million years ago, which is in agreement with all the scientific evidence.  Understanding the young earth creationist claims is key to being able to defend your beliefs.

     Old Earth Ministries has a page containing responses to young earth creationist claims, which can be found at this link.

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