Compsognathus

Kingdom: Animalia

Phylum: Chordata

Class: Reptilia

Order: Saurischia

Family: Compsognathidae

Genus: Compsognathus

Species: Compsognathus longpipes

Introduction

Compsognathus was a small, carnivorous dinosaur that lived in Late Jurassic Europe. At the time of its discovery in the 1860s, Compsognathus was the smallest known dinosaur, though subsequent excavations have revealed a number of smaller species.

During the Triassic period, the continents of the modern world were united in a single landmass, known as Pangaea. During the Jurassic period, the movement of tectonic plates caused Pangaea to split, giving rise to two supercontinents: Gondwana in the south contained most of the modern southern hemisphere, while Laurasia contained the land masses that would later become the northern hemisphere continents.

Compsognathus and many of its relatives first appear in the fossil record in the Jurassic, a time of intense geological change, when the supercontinents of Gondwana and Laurasia were beginning to split. Compsognathus was a member of a dinosaur group that spread around the world in the Late Triassic and Early to Middle Jurassic. By the Late Jurassic, related species were living on every continent.

Classification

Scientists use two primary methods to classify organisms into different groups. Linnaean taxonomy groups organisms heirarchically according to overall physical similarity and was used to create the basic categories of life, including grouping organisms into kingdoms, phylums, classes, orders, etc. Compsognathus was a member of the suborder Theropoda, the dominant suborder of carnivorous dinosaurs throughout the Mesozoic. Within this suborder, Compsognathus was related to the groups of dinosaurs that later led to the evolution of birds. In addition to the genus Compsognathus, the family Compsognathidae also contains several other genera of small carnivores, including Juravenator and Huaxiagnathus.

An alternate system, called “cladistics,” attempts to create groups of organisms that better reflect the evolutionary relationships between species. Cladistics uses key traits to classify animals into “clades,” groups that contain species that share common ancestry. Compsognathus typically finds itself classified with coelurosaurs in a cladistic analysis of Theropoda, as they share features such as a stiffened tails near the hip, larger brains, three-fingered hands, compressed metatarsals on a slender foot, and a tibia that is longer than the femur.

Anatomy

Compsognathus was a small dinosaur, measuring 0.8 to 1 meter (2.5–3.2 ft) in length and standing about 26 centimeters (10 in) at the hips. Adults weighed between 2 and 2.8 kilograms (4–6 lbs), which is similar to a large bird or a small cat or dog. Though smaller dinosaurs have been discovered, Compsognathus remains one of the smallest dinosaurs on record.

The animal was bipedal, with longer hind limbs than forelimbs. It possessed three fingers on both its front and rear legs, with pronounced claws. The animal's skull was lightly built, with forward facing eyes and an extended, tapered muzzle. The animal had relatively large eyes for its skull size. The jaws were lined with rows of sharp teeth.

Specimens of Compsognathus have been found with impressions of soft tissue, indicating that the animal had fine, mosaic scales over most of its body. Some impressions indicate the presence of small protuberances from the skin, which may have held feathers or protofeathers (feather-like scales).

Intelligence

While the EQ for Compsognathus has not been calculated, most theropods had EQ ratings ranging from 1.0 to 2.0, which is significantly higher than the 0.5 to 1.0 range given for many of the herbivores that lived alongside Compsognathus in Jurassic Europe. Generally speaking, predatory animals have higher intelligence than their prey, enabling them to outsmart their next meal. Compsognathus may have had similar intelligence to some modern types of small insectivorous birds.

Reproduction and Population

Paleontologists believe that Compsognathus laid eggs, though no specimens have been found with eggs or young. The discovery of closely related species Sinosauropteryx in China revealed two preserved eggs within its oviducts. Paleontologists surmise that Compsognathus might also have laid small clutches of eggs like its Chinese relative.

Few specimens of Compsognathus have been found, leaving paleontologists with little evidence to estimate population size. No groups have been discovered, leading paleontologists to suggest that Compsognathus may have been a solitary animal, though there is no evidence to suggest how it may have behaved towards its young.

Diet

An examination of Compsognathus’ anatomy indicates that the animal was a predator, most likely hunting a variety of small animals, including reptiles, amphibians, and perhaps fish. Like most theropods, Compsognathus was armed with rows of sharp teeth, which were appropriate tools for predatory behavior.

Paleontologists have found Compsognathus fossils with lizards and other small animal skeletons still intact inside the stomach, indicating that the animal might have swallowed its prey whole.

Behavior

Compsognathus specimens have appeared as solo fossils, suggesting that the animal might have lived a solitary lifestyle. Paleontologists have suggested, based on the fossilized vegetation and other sediments found near Compsognathus specimens, that the animal lived among a system of semi-forested lagoons and open dunes on a series of islands.

Examinations of Compsognathus’ legs and hips indicate that it may have had a maximum running speed of up to 64 kilometers (almost 40 miles) per hour. Designed for rapid movement, the animal was able to capture fast-moving prey. Because the environment in which Compsognathus lived was covered in watery dunes, some studies suggest that the animal may have been adapted for swimming and capturing prey in shallow water. Both its grasping arms and short pointed teeth would have enabled it to capture and kill fish and small reptiles.

Habitat and Other Life Forms

During the Late Jurassic, a sea flooded much of what would become Europe and Russia and connected the inland sea known as the Tethys to the Atlantic Ocean. Temperatures were warmer than in the modern period, with lush tropical forests and scrub plain found across the world.

Late Jurassic vegetation in Europe consisted primarily of gymnosperms, as flowering plants would not develop until the Cretaceous period. There were a variety of small mammals, lizards, and amphibians, similar to modern species found in subtropical environments. There were few birds and no flying mammals, but the skies were occupied with insects and reptiles known as pterosaurs, which filled the niches occupied by modern birds and bats.

Compsognathus appears to have been a common small predator in Late Jurassic Europe, but lived alongside much larger theropod dinosaurs, including the dominant carnosaur Allosaurus and its slightly smaller cousin Ceratosaurus. Among the herbivores that lived in the environment were several species of sauropods, the large herbivorous dinosaurs that include Brachiosaurus and Camarasaurus. There were also a variety of smaller dinosaurs occupying the same area, like Camptosaurus, a smaller, beaked herbivore.

Research

Compsognathus was first discovered in Germany, with another specimen later discovered in France. The species was first described by Johann A. Wagner in 1859. In 1896, Othniel Marsh studied the species and placed it within the dinosaur group, while previously it had been identified as a possible bird. Paleontologists long debated whether the French and German specimens were the same species. Examinations conducted in 2005 and 2006 indicated that the French and German specimens represent the same species and that skeletal variation between the two specimens is consistent with variation in a single species. As the original fossil of the Compsognathus continued to be studied, its existence may have provided further insight into other creatures as well. In a paper published in the Zoological Journal of the Linnean Society in 2018, Jack Conrad argued that analysis of the skull anatomy of the lizard fossil found in the stomach of Compsognathus indicated that the lizard should belong to a new species rather than the one it had long been believed to belong to.

Bibliography

Briggs, Derek E. G., and Peter R. Crowther. Paleobiology II. Wiley-Blackwell, 2001.

Chiappe, Luis M., and Lawrence M. Witmer. Mesozoic Birds: Above the Heads of Dinosaurs. U of California P, 2002.

"Compsognathus." Natural History Museum, www.nhm.ac.uk/discover/dino-directory/compsognathus.html. Accessed 28 Apr. 2020.

Conrad, Jack L. "A New Lizard (Squamata) Was the Last Meal of Compsognathus (Theropoda: Dinosauria) and Is a Holotype in a Holotype." Zoological Journal of the Linnean Society, vol. 183, no. 3, 2018, pp. 584–634.

Fastovsky, David E., and David B. Weishampel. Dinosaurs: A Concise Natural History. 3rd ed., Cambridge UP, 2016.

Fastovsky, David E., and David B. Weishampel. Evolution and Extinction of the Dinosaurs. 2nd ed., Cambridge UP, 2007.

Horner, Jack, and James Gorman. How to Build a Dinosaur: Extinction Doesn’t Have to Be Forever. Dutton, 2009.

Horner, John R., and Edwin Dobb. Dinosaur Lives: Unearthing an Evolutionary Saga. Mariner Books, 1998.

Long, John, and Peter Schouten. Feathered Dinosaurs: The Origin of Birds. Oxford UP, 2008.

Lucas, Spencer G. Dinosaurs: The Textbook. 6th ed., Columbia UP, 2016.

"The Major Groups of Coelurosaurs." University of California Museum of Paleontology, www.ucmp.berkeley.edu/diapsids/saurischia/coelurosauria.html. Accessed Feb. 2010.

Martin, Anthony J. Introduction to the Study of Dinosaurs. 2nd ed., Blackwell, 2006.

“The Relationships Between Dinosaurs and Birds.” Science, vol. 6, 1885, p. 295.

Sellers, William Irvin, and Phillip Lars Manning. “Estimating Dinosaur Maximum Running Speeds Using Evolutionary Robotics.” Proceedings of the Royal Society of Biology, vol. 274, 2007, pp. 2711–16.

Weishampel, David B., et al., editors. The Dinosauria. 2nd ed., U of California P, 2004.