Fossil Friday: Allosaurus

Species: Allosaurus fragilis (ah-loe-sore-us frrah-gee-lees)

What it means: Strange reptile

Other Species: A. europaeus, A. jimmadseni

Where I live: Western U.S.A.- The Morrison Formation / Portugal – The Lourinha Formation

When to find me: The Late Jurassic period, about 155 million years ago.

My favorite food: Meat! I’m a carnivore.

My neighborhood: The Morrison Formation covers a huge expanse of land with a variety of different habitats teaming with life. Most of it was very much like the Serengeti of modern day Africa, only with prairies of drought-tolerant ferns and cycad relatives instead of grass. Dense woodlands of tall conifers like the modern araucaria, ginkgoes, and tree ferns would only lie in places of plentiful water such as the few permanent rivers. Other areas had far more sparse and shrubbier vegetation like the open woodlands of acacia trees in the Serengetti.

Life in this environment would’ve adapted to long months of harsh drought, followed by a few months of monsoon that flooded the rivers. Many of the larger herbivores may have migrated like the herds in Africa do today, while most carnivores stayed behind to feast on the dead and dying, or else become opportunistic hunters of less traditional diets for lean times, such as fish or turtles in the rivers.

A few of my neighbors: First let me share the walking buffet…

  • Long-necked sauropods like Brachiosaurus, Camarasaurus, Diplodocus, Barosaurus, Apatosaurus, Suuwassea, Supersaurus, Haplocanthosaurus, and Dystrophaeus.
  • Armored dinosaurs like Stegosaurus, Hesperosaurus, Mymoorapelta, and Gargoyleosaurus.
  • Two-legged ornithopods like Dryosaurus, Camptosaurus, and Nanosaurus

At the buffet I can meet all sorts of fellow carnivores, including dinosaurs like Torvosaurus, Ceratosaurus, Saurophaganax, Marshosaurus, Stokesaurus, Ornitholestes, Coelurus, Tanycolagreus, Elaphrosaurus, and Koparion.

Not to mention the countless lizards, crocodile relatives on land and water, mammals, frogs, turtles, fish, and all the pterosaurs flying in the sky!

Fun Facts:

  • Allosaurus gets its name from allos (Greek for strange, or different) + sauros (Greek for lizard or reptile). The name for the type species is fragilis, the Latin word for fragile, because of the birdlike features in its vertebrae.
  • Allosaurus was the most numerous carnivore in the Morrison Formation. Out of 190 known specimens of theropod dinosaurs, Allosaurus accounts for nearly 75% of that number.
  • Allosaurus is one of the many dinosaurs from the Morrison Formation discovered during the “Bone Wars”, a period of competition between paleontologists Edward Drinker Cope and Othniel Charles Marsh in the late 19th century. Othniel Charles Marsh first described the bones of Allosaurus in 1877.
  • The first bones ever found where thought to be “petrified horse hooves” by the locals, before it was sent to paleontologist Joseph Leidy, who identified the fossil as half a tail vertebrae and named it Antrodemus.
  • During the “Bone Wars” many dinosaurs were named from bones of the same animals. Most of the time because of miscommunication with their own teams over fragmentary fossils, and partially to “one up” each other, though this rivalry wasn’t quite as vicious as many sources claim. (Aside from destroying quarries rather than risk the other finding fossils there). Allosaurus received several names at this time- Marsh’s Creosaurus and Labrosaurus, and Cope’s Epanterias.
  • For over 50 years all the Allosaurus remains were joined under the name of the first known fossil, Antrodemus. But a single tail vertebrae is not enough to identify a genus of dinosaur, plus no one knew where the original bone was found, and so it was officially reclassified as Allosaurus by James Madsen, who published on a huge bonebed of Allosaurus from the Cleveland-Lloyd Dinosaur Quarry. More famously known as Dinosaur National Monument.

Fossil Finds: Numerous remains from many individuals, ranging from fragmentary bones to almost complete and perfect skeletons. There may be more Allosaurus fossils than any other large theropod (two-legged, generally carnivorous dinosaur). Many fossils include pathologies, or signs of injury and illness the dinosaur suffered during its lifetime. More than almost any other large theropod, we can understand a lot about how it grew and lived in its environment.


Madsen, James H., Jr. (1993) [1976]. Allosaurus fragilis: A Revised Osteology. Utah Geological Survey Bulletin 109 (2nd ed.). Salt Lake City: Utah Geological Survey.

Foster, John. Jurassic West: The Dinosaurs of the Morrison Formation and Their World. Indiana University Press, 2007

“Allosaurus.” Wikipedia,

Fossil Friday: Insects Part 6

Here we are at the final chapter of Jurassic Insects! Today I’ll be exploring crickets, grasshoppers, and lacewings. Grasshoppers did not appear as we know them today until the Jurassic (though there are plenty of grasshopper-ish things, as usual), but Crickets and Lacewings are known from the Permian. In both of these groups there are many families I have not included here, because if I did we’d be sitting on another post for each of them! So after a brief look down below, I encourage you to take a look at the resources and see the amazing variety of crickets and lacewings that survive to the modern day.

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Fossil Friday: Insects Part 5

Next week will be the last part in this series of Jurassic insects. I really did try to fit all the rest of them in this post, but when I saw how many different families were in with grasshoppers, crickets, and lacewings, I had to have a post just for them. So if you can bear with me for just a bit longer with all these bugs, we’ll explore a few true bugs and other insects crawling into the kitchen sink for this round.

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Critter of the Month: Archaeopteryx

Meet Tango. This bird likes to party, and loves being the center of attention even more!

We’ve been working on my big boy’s reading skills, and he’s been struggling to focus on some of the stories in his workbook. To be perfectly frank, they’re not really stories so much as exposition on a particular topic. What’s exposition, you ask? In a word…boring! So I thought I’d write a few silly stories of my own for him to read!

Here’s the first little section. I’ll have it finished and post the complete story with the next critter of the month. Keep in mind this is for a beginning reader, so some sight words and words that he can sound out lol 😀

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