Giraffatitan
Encyclopedia
Giraffatitan, meaning "giraffe
titan", is a genus
of sauropod dinosaur
that lived during the late Jurassic
Period (Kimmeridgian
-Tithonian
stages). It was originally named as an African species of Brachiosaurus
(B. brancai). Giraffatitan was one of the largest animals known to have walked the earth.
dinosaurs with long neck
s and tail
s and relatively small brain
s. It had a giraffe
-like build, with long forelimbs and a very long neck. The skull had a tall arch anterior
to the eyes, consisting of the bony nares, a number of other openings, and "spatulate" teeth (resembling chisels). The first toe on its front foot and the first three toes on its hind feet were claw
ed.
Traditionally, the distinctive high-crested skull has been seen as a characteristic of the genus Brachiosaurus to which Giraffatitan brancai was originally referred, but because within the traditional Brachiosaurus material it is known only from Tanzanian specimens now assigned to Giraffatitan, it is possible that Brachiosaurus altithorax did not show this feature.
, even though Amphicoelias
was found earlier. It has since been discovered that a number of giant titanosaur
ians (for example Argentinosaurus
, Puertasaurus
and Futalognkosaurus) surpassed Giraffatitan in terms of sheer mass. Nor is Giraffatitan the largest known brachiosaurid
: based on incomplete fossil
evidence, Sauroposeidon
too is likely to have outweighed Giraffatitan. However, Giraffatitan is the largest dinosaur known from relatively complete material. Based on a composite skeleton, Giraffititan attained 26 metres (85.3 ft) in length.
Historically, G. brancai has been estimated to have weighed as little as 15 tonnes (16.5 ST) and as much as 78.26 tonnes (86.3 ST). These extreme estimates are now considered unlikely. The smaller, 15t estimate (by Dale Russell
and colleagues in 1980) was based on scaling up limb bones based on smaller specimens, rather than a body model, and the larger, 78t estimate (by Edwin Harris Colbert
in 1962) was based on an outdated and overweight model. More recent estimates based on models reconstructed from bone volume measurements (which take into account the extensive, weight-reducing air sac systems present in sauropods) and estimated muscle mass are in the range of 23 tonnes (25.4 ST) to 37 tonnes (40.8 ST).
in 1914 as Brachiosaurus brancai, based on several specimens recovered between 1909 and 1912 from the Tendaguru
formation near Lindi
, in what was then German East Africa
, today Tanzania
. It is known from five partial skeletons, including three skulls and numerous fragmentary remains including skull material, some limb bones, vertebrae and teeth. It lived from 145 to 150 million years ago, during the Kimmeridgian to Tithonian ages of the Late Jurassic period.
In 1988, Gregory S. Paul
noted that Brachiosaurus brancai (on which most popular depictions of Brachiosaurus were based) showed significant differences from the North American Brachiosaurus, especially in the proportions of its trunk vertebrae and in its more gracile build. Paul used these differences to create a subgenus he named Brachiosaurus (Giraffatitan) brancai. In 1991, George Olshevsky asserted that these differences were enough to place the African brachiosaurid in its own genus, simply Giraffatitan.
Further differences between the African and North American forms came to light with the description in 1998 of a North American Brachiosaurus skull. This skull, which had been found nearly a century earlier (it is the skull Marsh
used on his early reconstructions of Brontosaurus
), is identified as "Brachiosaurus sp." and may well belong to B. altithorax. The skull is closer to Camarasaurus
in some features such as the form of the front teeth and more elongated and less hollowed-out on top than the distinctive short-snouted and high-crested skull of Giraffatitan.
The classification of Giraffatitan as a separate genus was not widely followed by other scientists at first, as it was not supported by a rigorous comparison of both species. However, a detailed comparison was published by Michael Taylor in 2009. Taylor showed that "Brachiosaurus" brancai differed from B. altithorax in almost every fossil bone that could be compared, in terms of both size, shape, and proportion, finding that the placement of Giraffatitan in a separate genus was valid.
, when its massive body size is taken into account, of about 300 cm³. A 2009 study calculated its brain-to-body mass ratio (a rough estimate of possible intelligence) at a low 0.62 or 0.79, depending on the size estimate used. Giraffatitan is also similar to other sauropods in having an enlargement of the spinal cord above the hips, which some older sources misleadingly referred to as a "second brain".
(warm-blooded), it would have taken an estimated ten years to reach full size, if it were instead poikilothermic
(cold-blooded), then it would have required over 100 years to reach full size. As a warm-blooded animal, the daily energy demands of Giraffatitan would have been enormous; it would probably have needed to eat more than ~182 kg (400 lb) of food per day. If Giraffatitan was fully cold-blooded or was a passive bulk endotherm
, it would have needed far less food to meet its daily energy needs. Some scientists have proposed that large dinosaurs like Giraffatitan were gigantotherms
.
The nostril
s of Giraffatitan, like the huge corresponding nasal openings in its skull, were long thought to be located on the top of the head. In past decades, scientists theorized that the animal used its nostrils like a snorkel
, spending most of its time submerged in water in order to support its great mass. The current consensus view, however, is that Giraffatitan was a fully terrestrial animal
. Studies have demonstrated that water pressure would have prevented the animal from breathing effectively while submerged and that its feet were too narrow for efficient aquatic use. Furthermore, new studies by Lawrence Witmer (2001) show that, while the nasal openings in the skull were placed high above the eyes, the nostrils would still have been close to the tip of the snout (a study which also lends support to the idea that the tall "crests" of brachiosaurs supported some sort of fleshy resonating chamber).
A famous specimen of Giraffatitan brancai mounted in Museum für Naturkunde (Berlin
) is one of the largest, and in fact the tallest, mounted skeletons in the world, as certified by the Guinness Book of Records. Beginning in 1909, Werner Janensch found many additional G. brancai specimens in Tanzania, Africa, including some nearly complete skeletons, and used them to create the composite mounted skeleton seen today.
Giraffe
The giraffe is an African even-toed ungulate mammal, the tallest of all extant land-living animal species, and the largest ruminant...
titan", is a genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of sauropod dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...
that lived during the late Jurassic
Jurassic
The Jurassic is a geologic period and system that extends from about Mya to Mya, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the age of reptiles. The start of the period is marked by...
Period (Kimmeridgian
Kimmeridgian
In the geologic timescale, the Kimmeridgian is an age or stage in the Late or Upper Jurassic epoch or series. It spans the time between 155.7 ± 4 Ma and 150.8 ± 4 Ma . The Kimmeridgian follows the Oxfordian and precedes the Tithonian....
-Tithonian
Tithonian
In the geologic timescale the Tithonian is the latest age of the Late Jurassic epoch or the uppermost stage of the Upper Jurassic series. It spans the time between 150.8 ± 4 Ma and 145.5 ± 4 Ma...
stages). It was originally named as an African species of Brachiosaurus
Brachiosaurus
Brachiosaurus is a genus of sauropod dinosaur from the Jurassic Morrison Formation of North America. It was first described by Elmer S. Riggs in 1903 from fossils found in the Grand River Canyon of western Colorado, in the United States. Riggs named the dinosaur Brachiosaurus altithorax,...
(B. brancai). Giraffatitan was one of the largest animals known to have walked the earth.
Description
Giraffatitan was a sauropod, one of a group of four-legged, plant-eatingHerbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...
dinosaurs with long neck
Neck
The neck is the part of the body, on many terrestrial or secondarily aquatic vertebrates, that distinguishes the head from the torso or trunk. The adjective signifying "of the neck" is cervical .-Boner anatomy: The cervical spine:The cervical portion of the human spine comprises seven boney...
s and tail
Tail
The tail is the section at the rear end of an animal's body; in general, the term refers to a distinct, flexible appendage to the torso. It is the part of the body that corresponds roughly to the sacrum and coccyx in mammals, reptiles, and birds...
s and relatively small brain
Brain
The brain is the center of the nervous system in all vertebrate and most invertebrate animals—only a few primitive invertebrates such as sponges, jellyfish, sea squirts and starfishes do not have one. It is located in the head, usually close to primary sensory apparatus such as vision, hearing,...
s. It had a giraffe
Giraffe
The giraffe is an African even-toed ungulate mammal, the tallest of all extant land-living animal species, and the largest ruminant...
-like build, with long forelimbs and a very long neck. The skull had a tall arch anterior
Anatomical terms of location
Standard anatomical terms of location are designations employed in science that deal with the anatomy of animals to avoid ambiguities that might otherwise arise. They are not language-specific, and thus require no translation...
to the eyes, consisting of the bony nares, a number of other openings, and "spatulate" teeth (resembling chisels). The first toe on its front foot and the first three toes on its hind feet were claw
Claw
A claw is a curved, pointed appendage, found at the end of a toe or finger in most mammals, birds, and some reptiles. However, the word "claw" is also often used in reference to an invertebrate. Somewhat similar fine hooked structures are found in arthropods such as beetles and spiders, at the end...
ed.
Traditionally, the distinctive high-crested skull has been seen as a characteristic of the genus Brachiosaurus to which Giraffatitan brancai was originally referred, but because within the traditional Brachiosaurus material it is known only from Tanzanian specimens now assigned to Giraffatitan, it is possible that Brachiosaurus altithorax did not show this feature.
Size
For many decades, Giraffatitan was claimed to be the largest dinosaur knownLargest organisms
The largest organism found on Earth can be measured using a variety of methods. It could be defined as the largest by volume, mass, height or length. Some organisms group together to form a superorganism, though this cannot truly be classed as one large organism...
, even though Amphicoelias
Amphicoelias
Amphicoelias is a genus of herbivorous sauropod dinosaur that includes what may be the largest dinosaur ever discovered, A. fragillimus. Based on surviving descriptions of a single fossil bone, A. fragillimus may have been the longest known vertebrate at in length, and may have had a mass of up...
was found earlier. It has since been discovered that a number of giant titanosaur
Titanosaur
Titanosaurs were a diverse group of sauropod dinosaurs, which included Saltasaurus and Isisaurus. It includes some of the heaviest creatures ever to walk the earth, such as Argentinosaurus and Paralititan — which some believe have weighed up to 100 tonnes...
ians (for example Argentinosaurus
Argentinosaurus
Argentinosaurus is a genus of titanosaur sauropod dinosaur first discovered by Guillermo Heredia in Argentina. The generic name refers to the country in which it was discovered...
, Puertasaurus
Puertasaurus
Puertasaurus is a genus of titanosaurid sauropod that appeared during the Late Cretaceous. It lived in what is now Patagonia. The type species, Puertasaurus reuili, is named in honor of Pablo Puerta and Santiago Reuil, the co-discoverers in January 2001 of the specimen...
and Futalognkosaurus) surpassed Giraffatitan in terms of sheer mass. Nor is Giraffatitan the largest known brachiosaurid
Brachiosauridae
Brachiosauridae are a family of dinosaurs, whose members are known as brachiosaurids. They were herbivorous quadrupeds with longer forelegs than hind legs - the name derives from the Greek for arm lizard - and long necks...
: based on incomplete fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
evidence, Sauroposeidon
Sauroposeidon
Sauroposeidon is a genus of sauropod dinosaur known from four neck vertebrae that were found in the southeastern portion of the US state of Oklahoma. The fossils were found in rocks dating to the Early Cretaceous, a period when the sauropods of North America had diminished in both size and...
too is likely to have outweighed Giraffatitan. However, Giraffatitan is the largest dinosaur known from relatively complete material. Based on a composite skeleton, Giraffititan attained 26 metres (85.3 ft) in length.
Historically, G. brancai has been estimated to have weighed as little as 15 tonnes (16.5 ST) and as much as 78.26 tonnes (86.3 ST). These extreme estimates are now considered unlikely. The smaller, 15t estimate (by Dale Russell
Dale Russell
Dale A. Russell is a Canadian geologist/palaeontologist, currently Research Professor at The Department of Marine Earth and Atmospheric Sciences of North Carolina State University...
and colleagues in 1980) was based on scaling up limb bones based on smaller specimens, rather than a body model, and the larger, 78t estimate (by Edwin Harris Colbert
Edwin Harris Colbert
Edwin Harris Colbert was a distinguished American vertebrate paleontologist and prolific researcher and author. He received his A.B. from the University of Nebraska, then his Masters and Ph.D. from Columbia University, finishing in 1935.Born in Clarinda, Iowa, he grew up in Maryville, Missouri...
in 1962) was based on an outdated and overweight model. More recent estimates based on models reconstructed from bone volume measurements (which take into account the extensive, weight-reducing air sac systems present in sauropods) and estimated muscle mass are in the range of 23 tonnes (25.4 ST) to 37 tonnes (40.8 ST).
History and classification
Giraffatitan brancai was first named and described by German paleontologist Werner JanenschWerner Janensch
Werner Ernst Martin Janensch was a German paleontologist and geologist.Janensch's most famous contributions stemmed from the expedition he led with Edwin Hennig to the Tendaguru Beds in what is now Tanzania...
in 1914 as Brachiosaurus brancai, based on several specimens recovered between 1909 and 1912 from the Tendaguru
Tendaguru
The Tendaguru Beds are a fossil-rich formation in Tanzania. It has been considered the richest of Late Jurassic strata in Africa. Continental reconstructions show Tendaguru to have been in the southern hemisphere during the Late Jurassic. Tendaguru is similar to the Morrison Formation except in...
formation near Lindi
Lindi
Lindi is a coastal town located at the far end of the Lindi Bay, on the Indian Ocean in southeastern Tanzania. The town is 450 kilometers south of Dar es Salaam and 105 kilometers north of Mtwara, the southernmost coastal town in Tanzania, and gives its name to the surrounding Lindi Region, one...
, in what was then German East Africa
German East Africa
German East Africa was a German colony in East Africa, which included what are now :Burundi, :Rwanda and Tanganyika . Its area was , nearly three times the size of Germany today....
, today Tanzania
Tanzania
The United Republic of Tanzania is a country in East Africa bordered by Kenya and Uganda to the north, Rwanda, Burundi, and the Democratic Republic of the Congo to the west, and Zambia, Malawi, and Mozambique to the south. The country's eastern borders lie on the Indian Ocean.Tanzania is a state...
. It is known from five partial skeletons, including three skulls and numerous fragmentary remains including skull material, some limb bones, vertebrae and teeth. It lived from 145 to 150 million years ago, during the Kimmeridgian to Tithonian ages of the Late Jurassic period.
Gregory S. Paul
Gregory Scott Paul is a freelance researcher, author and illustrator who works in paleontology, and more recently has examined sociology and theology. He is best known for his work and research on theropod dinosaurs and his detailed illustrations, both live and skeletal...
noted that Brachiosaurus brancai (on which most popular depictions of Brachiosaurus were based) showed significant differences from the North American Brachiosaurus, especially in the proportions of its trunk vertebrae and in its more gracile build. Paul used these differences to create a subgenus he named Brachiosaurus (Giraffatitan) brancai. In 1991, George Olshevsky asserted that these differences were enough to place the African brachiosaurid in its own genus, simply Giraffatitan.
Further differences between the African and North American forms came to light with the description in 1998 of a North American Brachiosaurus skull. This skull, which had been found nearly a century earlier (it is the skull Marsh
Othniel Charles Marsh
Othniel Charles Marsh was an American paleontologist. Marsh was one of the preeminent scientists in the field; the discovery or description of dozens of news species and theories on the origins of birds are among his legacies.Born into a modest family, Marsh was able to afford higher education...
used on his early reconstructions of Brontosaurus
Apatosaurus
Apatosaurus , also known by the popular but scientifically deprecated synonym Brontosaurus, is a genus of sauropod dinosaur that lived from about 154 to 150 million years ago, during the Jurassic Period . It was one of the largest land animals that ever existed, with an average length of and a...
), is identified as "Brachiosaurus sp." and may well belong to B. altithorax. The skull is closer to Camarasaurus
Camarasaurus
Camarasaurus meaning 'chambered lizard', referring to the hollow chambers in its vertebrae was a genus of quadrupedal, herbivorous dinosaurs. It was the most common of the giant sauropods to be found in North America...
in some features such as the form of the front teeth and more elongated and less hollowed-out on top than the distinctive short-snouted and high-crested skull of Giraffatitan.
The classification of Giraffatitan as a separate genus was not widely followed by other scientists at first, as it was not supported by a rigorous comparison of both species. However, a detailed comparison was published by Michael Taylor in 2009. Taylor showed that "Brachiosaurus" brancai differed from B. altithorax in almost every fossil bone that could be compared, in terms of both size, shape, and proportion, finding that the placement of Giraffatitan in a separate genus was valid.
Brain
Like other sauropods, Giraffatitan had a relatively small brainBrain
The brain is the center of the nervous system in all vertebrate and most invertebrate animals—only a few primitive invertebrates such as sponges, jellyfish, sea squirts and starfishes do not have one. It is located in the head, usually close to primary sensory apparatus such as vision, hearing,...
, when its massive body size is taken into account, of about 300 cm³. A 2009 study calculated its brain-to-body mass ratio (a rough estimate of possible intelligence) at a low 0.62 or 0.79, depending on the size estimate used. Giraffatitan is also similar to other sauropods in having an enlargement of the spinal cord above the hips, which some older sources misleadingly referred to as a "second brain".
Metabolism
If Giraffatitan was endothermicWarm-blooded
The term warm-blooded is a colloquial term to describe animal species which have a relatively higher blood temperature, and maintain thermal homeostasis primarily through internal metabolic processes...
(warm-blooded), it would have taken an estimated ten years to reach full size, if it were instead poikilothermic
Poikilotherm
A poikilotherm is an organism whose internal temperature varies considerably. It is the opposite of a homeotherm, an organism which maintains thermal homeostasis. Usually the variation is a consequence of variation in the ambient environmental temperature...
(cold-blooded), then it would have required over 100 years to reach full size. As a warm-blooded animal, the daily energy demands of Giraffatitan would have been enormous; it would probably have needed to eat more than ~182 kg (400 lb) of food per day. If Giraffatitan was fully cold-blooded or was a passive bulk endotherm
Gigantothermy
Gigantothermy is a phenomenon with significance in biology and paleontology, whereby large, bulky ectothermic animals are more easily able to maintain a constant, relatively high body temperature than smaller animals by virtue of their smaller surface area to volume ratio...
, it would have needed far less food to meet its daily energy needs. Some scientists have proposed that large dinosaurs like Giraffatitan were gigantotherms
Gigantothermy
Gigantothermy is a phenomenon with significance in biology and paleontology, whereby large, bulky ectothermic animals are more easily able to maintain a constant, relatively high body temperature than smaller animals by virtue of their smaller surface area to volume ratio...
.
Environment and behavior
Nostril
A nostril is one of the two channels of the nose, from the point where they bifurcate to the external opening. In birds and mammals, they contain branched bones or cartilages called turbinates, whose function is to warm air on inhalation and remove moisture on exhalation...
s of Giraffatitan, like the huge corresponding nasal openings in its skull, were long thought to be located on the top of the head. In past decades, scientists theorized that the animal used its nostrils like a snorkel
Snorkeling
Snorkeling is the practice of swimming on or through a body of water while equipped with a diving mask, a shaped tube called a snorkel, and usually swimfins. In cooler waters, a wetsuit may also be worn...
, spending most of its time submerged in water in order to support its great mass. The current consensus view, however, is that Giraffatitan was a fully terrestrial animal
Terrestrial animal
Terrestrial animals are animals that live predominantly or entirely on land , as compared with aquatic animals, which live predominantly or entirely in the water , or amphibians, which rely on a combination of aquatic and terrestrial habitats...
. Studies have demonstrated that water pressure would have prevented the animal from breathing effectively while submerged and that its feet were too narrow for efficient aquatic use. Furthermore, new studies by Lawrence Witmer (2001) show that, while the nasal openings in the skull were placed high above the eyes, the nostrils would still have been close to the tip of the snout (a study which also lends support to the idea that the tall "crests" of brachiosaurs supported some sort of fleshy resonating chamber).
In culture
Berlin
Berlin is the capital city of Germany and is one of the 16 states of Germany. With a population of 3.45 million people, Berlin is Germany's largest city. It is the second most populous city proper and the seventh most populous urban area in the European Union...
) is one of the largest, and in fact the tallest, mounted skeletons in the world, as certified by the Guinness Book of Records. Beginning in 1909, Werner Janensch found many additional G. brancai specimens in Tanzania, Africa, including some nearly complete skeletons, and used them to create the composite mounted skeleton seen today.