Author's note: these pages were written some years ago. I am not planning to update them. For a more current coverage, see the link to palaeos com Palaeos website (to which many links on these pages point to anyway. More info here

Family Camarasauridae link to palaeos com Late Jurassic to link to palaeos com Middle Cretaceous
( link to palaeos com Kimmeridgian to link to palaeos com Barremian)

Camarosaurus as it may have appeared in life
Camarosaurus image (above) by Brenner Fishman

Originally (especially in old books on dinosaurs) the Brachiosaurs and Camarosaurs were grouped together, with the Diplodocids and Titanosaurs as a seperate branch. Both Brachiosaurs and Camarosaurs have long forelimbs, shortish tails, short high skulls, and more and broader teeth. More recently research has shown that the Titanosaurs are actually related to the Brachiosaurs, the Camarasaurs, Brachiosaurs, and Titanosaurs being collectively referred to as the clade Macronaria. In this respect the Camarasaurs are the most primitive of the Macronarians. However, they also are specialised in specific ways. The skull is short, blunt and relatively large. The teeth are large and spatulate or spoon-like. The neck very strong but inflexible, and apparently strongly upwardly-directed (an adaptation on browsing on trees, unlike the low-feeding diplodocids and euhelopids). A distinguishing mark is the "bifid" (split or two-branched) neural spines (i.e. the upward part of each vertebra is divided into two), the resulting U-shaped trough perhaps for the location of strong tendons. The forelimbs were not as elongated as in the Brachiosaurids, with the fore and hind legs are approximately the same length, the hind legs being only slightly longer. The tail is fairly short, relative to diplodocids. These animals appear to have lived in large herds.

Until fairely recently it was stated that Camarosaurus evolved from the Chinese Euhelopus, but it is more likely that the Chinese forms, with their extraordinarily elongated necks, represented a line of advanced Shunosaurs. Despite their unspecialised structure, Camarasaurs are not known before the early link to palaeos com Kimmeridgian epoch, and it is possible that they evolved either from basal Oxfordian Brachiosaurids, or from early Jobaria-like forms

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Guild/Ecological niche: gigantic terrestrial high browsing herbivores
Modern equivalent: elephant??? giraffe???
Time: link to palaeos com Kimmeridgian to link to palaeos com Barremian
Distribution: known with certainty only from Western and middle link to palaeos com Laurasia
Evolved from: ? Cetiosauridae or ? Basal Brachiosauridae
Replaced: Cetiosauridae
Replaced by: Titanosaurs
Extinction because of: Cenomonian mass-extinction event? Or Earlier?
Descendents: none
Linnean status: Family
Cladistic status: Monophyletic clade
Parent clade: Macronaria
Adult length: 14 to 18 meters
Adult weight: 10 to 25 tonnes
Preferred habitat/environment: seasonally dry floodplains
Activity period: mostly diurnal, but probably fed and was active almost 24 hours
Metabolism: endothermic when young? gigantotherms (homeotherms) when subadult and adult
Senses: Eyes large, facing sideways; very good all-round (≅270° ?) vision. Hearing and sense of smell moderate.
Intelligence: brain to weight ratio small, at low end of modern reptiles, consciousness guided largely by instinct
Preferred food: mainly conifers - foliage from middle branches, could not reach as high as brachiosaurs
Feeding behaviour: stood motionless or walked very slowly, sweeping neck and head in wide arcs to access all foliage within reach, leaves and twigs cut and crushed with teeth
Food Processing: food ground in gizzard; symbiotic microrganisms in gut process plant amterial
Social behavior: travelled in large herds
Possible Life Cycle: quasi r-strategist, nest excavated with hind feet, eggs covered with dirt or vegetation, then abandoned, young small, active, high metabolism (although perhaps not as high as brachiosaurs). Infant mortality high, but young fast-growing, as they grew larger their metabolism and growth-rate slowed, slowed, became typical gigantotherms, joined the herd as "teenagers"
Movement: erect stance, slow plodding gait. Unlikely to rear on hindlegs. Tererstrial only (poor swimmer).
Walking speed: probably about 3 or 4 kph
Running Speed: no more than 12 kph
Predators: none as healthy adult; young, sick, etc vulnerable to any large theropod
Defense against predators: height and good eyesight allowed early detection of predators; size and safety in herd a good defense, the neck was very strong and could be swung with great force, a single blow would kill a large theropod; stomping with forelegs or kicking with hind-legs could catch any unwary preditor that got to close; for young very rapid growth and possible camoflague markings only protection.

The following cladogram is a simplified version of the ones at Mikko's phylogeny site and Justin Tweet's Thescelosaurus! pages. I have also made the completely arbitrary assumption that the three species of Morrison Camarasaurs which suceed each other chronologically are also an evolutionary succession (a chronospecies so to speak). As usual among dinosaur taxa, there is a lot of generic oversplitting, and the three genera placed in this family are so similiar that they should perhaps be considered subgenera or even species of one genus.

   |--o Camarasauridae
   |  `--o Camarasaurus Cope, 1877d
   |     |-+- C. grandis (Marsh, 1877b) 
   |     |   `-+- C. lentus (Marsh, 1889a)
   |     |       `-- C. supremus Cope, 1877e
   |     |-- Lourinhasaurus alenquerensis (Lapparent & Zbyszewski, 1957)
   |     `-- Aragosaurus ischiaticus Sanz, Buscalioni, Casanovas & Santafe, 1987
   `-+-o Brachiosauridae 
       `--o Titanosauriformes

List of Species

Camarosaurus (Lourinhasaurus) alenquerensis (de Lapparent & Zbyszewski, 1957)

Horizon: Lourinhã Formation, Provincia do Estremadura and Provincia do Beira Litoral, Portugal
Age: early link to palaeos com Kimmeridgian
remains: partial postcrania, tail vertebrae, teeth
estimated length: 17 metres
estimated mass: 15 to 20 tonnes

comments: Previously mistaken for Apatosaurus, this giant sauropod was one of the first of the Camarosaurids. This species, a robust, average camarasaurid, has recently been placed in a new genus, Lourinhasaurus

Lourinhasaurus page

Aragosaurus ischiaticus Sanz, Buscalioni, Casanovas, and Santafe, 1987

Age: early link to palaeos com Barremian
Place: central link to palaeos com Laurasia (Spain)
remains: postcranial elements (forelimb, scapula, partial tail, and partial hip)
Length: 18 metres
Weight: 18 to 25 tonnes

comments: Aragosaurus is very similiar to Camarasaurus, and, in view of its later occurance, may be a descendent. It is a very large animal, and shows that Camarasaurs, although suffering local extinctions, happened to survive the terminal Jurassic event quite well.

Camarasaurus skeleton
total length 18 metres

Camarosaurus grandis (Marsh 1877)

Synonyms: "Apatosaurus", Morosaurus, Pleurocoelus
Horizon: Morrison Formation; Wyoming, Colorado and Montana, United States
Age: Middle link to palaeos com Kimmeridgian
Place: western link to palaeos com Laurasia
remains: At least 6 partial skeletons, 2 with skulls; hundreds of postcranial elements
Length: 14 metres
Weight: 10 to 15 tonnes

Comments: a number of juveniles are known

Camarosaurus lentus (Marsh 1889)

Synonyms: Morosaurus, Uintasaurus
Horizon: Morrison Formation; Wyoming and Utah, United States
Age: Late link to palaeos com Kimmeridgian
Place: western link to palaeos com Laurasia
remains: 5 skeletons with skulls; hundreds of postcranial elements
Length: 14 metres
Weight: 10 to 15 tonnes

Comments: This animal was extremely common and dominated the megafauna of the region

Camarosaurus supremus Cope, 1877e

Horizon: Morrison Formation; Wyoming, Colorado and New Mexico
Age: Early link to palaeos com Tithonian

Place: western link to palaeos com Laurasia
remains: At least five partial skeletons
Length: 18 metres
Weight: 18 to 25 tonnes

Comments: The last and largest of the American Camarasaurs

Web links Links Web links

cladogram Camarasauridae - Thescelosaurus!

links link to palaeos com Camarasauridae - Palaeos

Dinosauricon Dinosauricon

cladogram Macronaria Mikko's phylogeny site

up one node (internal link) back to Sauropoda

Dinosaur main page
main page

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page history

page uploaded 12 November 1998
revised 12 May 1999
and 18 Feb 2000
converted to css format and made into new page with additional material 22 November 2000
further modified 1 December

content and html by M.Alan Kazlev