''Giraffatitan'' (name meaning "titanic
giraffe
The giraffe is a large Fauna of Africa, African even-toed ungulate, hoofed mammal belonging to the genus ''Giraffa.'' It is the Largest mammals#Even-toed Ungulates (Artiodactyla), tallest living terrestrial animal and the largest ruminant on ...
") is a genus of
sauropod
Sauropoda (), whose members are known as sauropods (; from '' sauro-'' + '' -pod'', 'lizard-footed'), is a clade of saurischian ('lizard-hipped') dinosaurs. Sauropods had very long necks, long tails, small heads (relative to the rest of their b ...
dinosaur
Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic Geological period, period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the #Evolutio ...
that lived during the late
Jurassic
The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately 143.1 Mya. ...
Period (
Kimmeridgian–
Tithonian
In the geological timescale, the Tithonian is the latest age (geology), age of the Late Jurassic Epoch and the uppermost stage (stratigraphy), stage of the Upper Jurassic Series. It spans the time between 149.2 ±0.7 annum, Ma and 143.1 ±0.6 (mi ...
stages) in what is now
Lindi Region
Lindi Region (''Mkoa wa Lindi'' in Swahili language, Swahili) is one of Tanzania's 31 administrative Regions of Tanzania, regions. The region covers an area of . The region is comparable in size to the combined land area of the nation state of Sr ...
,
Tanzania
Tanzania, officially the United Republic of Tanzania, is a country in East Africa within the African Great Lakes region. It is bordered by Uganda to the northwest; Kenya to the northeast; the Indian Ocean to the east; Mozambique and Malawi to t ...
. Only one species is known, ''G. brancai'', named in honor of
German paleontologist
Paleontology, also spelled as palaeontology or palæontology, is the scientific study of the life of the past, mainly but not exclusively through the study of fossils. Paleontologists use fossils as a means to classify organisms, measure geolo ...
Wilhelm von Branca, who was a driving force behind the expedition that discovered it in the
Tendaguru Formation. ''Giraffatitan brancai'' was originally described by German paleontologist
Werner Janensch as a species of the
North American sauropod ''
Brachiosaurus
''Brachiosaurus'' () is a genus of sauropod dinosaur that lived in North America during the Late Jurassic, about . It was first Species description, described by American paleontologist Elmer S. Riggs in 1903 in paleontology, 1903 from fossi ...
'' from the
Morrison Formation, as ''Brachiosaurus brancai''. Recent research shows that the differences between the
type species
In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...
of ''Brachiosaurus'' and the Tendaguru material are so large that the African material should be placed in a separate genus.
''Giraffatitan'' was for many decades known as the largest dinosaur but recent discoveries of several larger dinosaurs prove otherwise; giant
titanosaurians appear to have surpassed ''Giraffatitan'' in terms of sheer mass. Also, the sauropod dinosaur ''
Sauroposeidon'' is estimated to be taller and possibly heavier than ''Giraffatitan''. Most size estimates for ''Giraffatitan'' are based on the specimen HMN SII, a subadult individual, but there is evidence supporting that these animals could grow larger; specimen HMN XV2, represented by a fibula 13% larger than the corresponding material on HMN SII, would have measured around long and weighed about .
History of discovery
In 1906, mining engineer Bernhard Wilhelm Sattler, while travelling, noticed an enormous bone jutting out of the ground at the Tendaguru (the "steep hill") near
Lindi, in what was then
German East Africa, today
Lindi Region
Lindi Region (''Mkoa wa Lindi'' in Swahili language, Swahili) is one of Tanzania's 31 administrative Regions of Tanzania, regions. The region covers an area of . The region is comparable in size to the combined land area of the nation state of Sr ...
,
Tanzania
Tanzania, officially the United Republic of Tanzania, is a country in East Africa within the African Great Lakes region. It is bordered by Uganda to the northwest; Kenya to the northeast; the Indian Ocean to the east; Mozambique and Malawi to t ...
. In early 1907, his superior Wilhelm Arning in
Hannover
Hanover ( ; ; ) is the capital and largest city of the States of Germany, German state of Lower Saxony. Its population of 535,932 (2021) makes it the List of cities in Germany by population, 13th-largest city in Germany as well as the fourth-l ...
received a report on the find. Arning again informed the ''Kommission für die landeskundliche Erforschung der Schutzgebiete'', a commission in Berlin overviewing the geographical investigation of German protectorates. The German secretary of state of colonies,
Berhard Dernburg, at the time visited German East Africa accompanied by the industrialist
Heinrich Otto. Otto had invited the paleontologist Professor
Eberhard Fraas to join him as a scientific advisor. In the summer of 1907, Fraas, already for some months travelling the colony, received a letter from Dr Hans Meyer in
Leipzig
Leipzig (, ; ; Upper Saxon: ; ) is the most populous city in the States of Germany, German state of Saxony. The city has a population of 628,718 inhabitants as of 2023. It is the List of cities in Germany by population, eighth-largest city in Ge ...
urging him to investigate Sattler's discovery. On 30 August, Fraas arrived by steamer at the coastal town of Lindi. A five-day march brought him to the Tendaguru, where he could confirm that the bones were authentic and dinosaurian. Soon Sattler joined him with a team of native miners who uncovered two large sauropod skeletons which were transported to Germany. Ultimately, these would become the holotypes of the genera ''
Tornieria'' and ''
Janenschia''.
Fraas had observed that the Tendaguru layers were exceptionally rich in fossils. After his return to Germany he tried to raise enough money for a major expedition. He managed to attract the interest of Professor
Wilhelm von Branca, the head of the ''
Geologisch-Paläontologische Institut und Museum der Königliche Friedrich-Wilhelm Universität zu Berlin''. Von Branca considered it a matter of German national pride that such a project would succeed. He involved the well-connected pathologist
David von Hansemann. Von Hansemann founded a Tendaguru Committee headed by
Johann Albrecht, the
duke of Mecklenburg. Soon it became fashionable to join this committee which counted a large number of prominent German industrialists and scientists among its members. Many of their rich friends donated considerable sums. To lead the expedition, von Branca sent out one of his curators,
Werner Janensch, and one of his assistants,
Edwin Hennig. Both men arrived in
Dar es Salaam
Dar es Salaam (, ; from ) is the largest city and financial hub of Tanzania. It is also the capital of the Dar es Salaam Region. With a population of over 7 million people, Dar es Salaam is the largest city in East Africa by population and the ...
on 2 April 1909.
The expedition initially employed about 160 native
porters, as
beasts of burden
A working animal is an animal, usually domesticated, that is kept by humans and trained to perform tasks. Some are used for their physical strength (e.g. oxen and draft horses) or for transportation (e.g. riding horses and camels), while oth ...
could not be used because of the danger posed by the
tse tse fly. During four field seasons, of 1909, 1910, 1911 and 1912, about a hundred paleontological quarries were opened. Large amounts of fossil material were shipped to Germany. Soon it became evident that apart from ''Tornieria'' and ''Janenschia'', other sauropods were present in the layers. One was the medium-sized ''
Dicraeosaurus'', a relatively common find. More rare was a gigantic form that far surpassed the others in magnitude and that is today known as ''Giraffatitan''. The first quarry with ''Giraffatitan'' material was "Site D", located about one kilometre northeast of the Tendaguru Hill and opened on 21 June 1909. It contained a relatively complete skeleton of a medium-sized individual, lacking the hands, the neck, the back vertebrae and the skull. It included an articulated series of twenty-nine tail vertebrae. The other bones were found in close association on a surface of twenty-two square metres. "Site IX", located 1.4 kilometres northeast of the Tendaguru Hill, was opened on 17 August 1909. Among an assemblage of 150 disarticulated dinosaur bones, also two ''Giraffatitan'' thighbones were present. The next ''Giraffatitan'' quarry was "Site N", at nine hundred metres east of the Tendaguru Hill, excavated in September 1909. It held a single disarticulated skeleton containing a back vertebra, a tail vertebra, ribs, a scapula, a possible scapula, a humerus, two ischia and a number of unidentifiable bones.
The most important source of ''Giraffatitan'' fossils would be "Site S" at one kilometre southwest of the hill. Excavations started on 11 October 1909 and continued well into 1912. In 1909 limb and girdle elements were dug up. During 1910, a
cut bank of the Kitukituki river was gradually deepened, removing a high overburden. To prevent the quarry walls from collapsing, they were covered by a high wooden framework. That year, first several ribs were uncovered and later part of the vertebral column. In October, close to some neck vertebrae a skull and lower jaws were discovered. From 5 June 1912 onwards more neck and trunk vertebrae were found. Initially it was thought that a single skeleton was being uncovered. Only much later Janensch realised that two skeletons had been present. ''Skelett'' SI was represented by a skull, six neck vertebrae and some back vertebrae. ''Skelett'' SII was larger but despite its size still a subadult individual. It included skull bones, a series of eleven neck and eleven back vertebrae, ribs, the left scapula, both coracoids, both forelimbs, the pubic bones and the right hindlimb. The sacrum and the tail had been lost to relatively recent erosion. The animal was found in an upright position with vertical limbs, which has been explained by its becoming mired in mud.

In early October 1909, "Site ab" was excavated, 1.2 kilometres northeast of the hill. Among disarticulated remains of many sauropods, also two ''Giraffatitan'' thighbones were collected. A gigantic possible humerus was too damaged to be salvaged. "Site cc", 2.9 kilometres northeast of the hill, contained a disarticulated ''Giraffatitan'' skeleton including neck vertebrae, a trunk vertebra, ribs, a scapula and a humerus. In 1910, another ''Giraffatitan'' quarry was opened, "Site Y" at 3.1 kilometres north of the Tendaguru Hill. It contained the skeleton of a medium-sized individual including a braincase, a series of eight neck vertebrae, a trunk vertebra, ribs, both scapulae, a coracoid, a left humerus and a left fibula.
A partial skeleton called "Skelett Y" (skeleton Y) was discovered in quarry "Y". On the basis of its scapula (shoulder blade) and humerus (upper arm bone) ''Brachiosaurus fraasi'' was erected, which later turned out to be a junior synonym of ''B. brancai''. From quarry "D" came 23 vertebrae articulated with a sacrum (a hip bone), from quarry "Aa" another 18 vertebrae with a sacrum, from quarry "no" 50 articulated tail vertebrae, from GI 16 tail vertebrae and a number of limb bones, and much more material from other places, including many limb elements.
The quarries listed above represent only the most important sites where bones were found. In dozens of other Tendaguru locations, finds were made of large single sauropod bones that were referred to the taxon in Janensch's publications but of which no field notes survive so that the precise circumstances of the discoveries are unknown. Partly this reflects a lack of systematic documentation by the expedition. Many documents were destroyed by an allied bombardment in 1943. Part of the fossils were also lost. Nevertheless, most of the skeleton is known.

''Giraffatitan brancai'' was first named and described by German paleontologist Werner Janensch in 1914 as ''Brachiosaurus brancai'', based on several specimens recovered between 1909 and 1912 from the
Tendaguru formation.
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. The lectotype material of ''Giraffatitan brancai'' is skeleton "Skelett SII", a partial skeleton from Tendaguru. It consists of skull fragments including dentaries, eleven cervical vertebrae, cervical ribs, seven dorsal vertebrae, nearly complete set of dorsal ribs, distal caudal vertebrae, chevrons, left scapula, both coracoids and sternal plates, right forelimb (except the humerus, which is probably from a referred specimen from quarry "Ni") and manus, left humerus, ulna and radius, both pubes, partial left femur, right tibia and fibula.
[ "Skelett SI" is a paralectotype, and consists of a skull and six cervical (neck) vertebrae.][
Originally, the Tedaguru "Skelett S" was thought by Janensch to stem from one animal, and to be very similar to the North American genus ''Brachiosaurus''. Therefore, Janensch described it as ''Brachiosaurus brancai'', choosing the species name in honor of Wilhelm von Branca, then director of the ]Museum für Naturkunde
The Natural History Museum () is a natural history museum located in Berlin, Germany. It exhibits a vast range of specimens from various segments of natural history and in such domain it is one of three major museums in Germany alongside Naturm ...
and a driving force behind the Tendaguru expedition.[ Later, Janensch realized that the remains pertained to two separate animals, "Skelett SI" (skeleton S1) and "Skelett SII" (skeleton S2) both of which belonged to the same species. Janensch did not designate either of the two as lectotype, and Taylor in 2009 selected the more complete "Skellet S II" as the lectotype.][
A famous specimen of ''Giraffatitan brancai'' mounted in the Berlin's Natural History Museum 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.
]
Separation from ''Brachiosaurus''
In 1988 Gregory S. Paul
Gregory Scott Paul (born December 24, 1954) is an American freelance researcher, author and illustrator who works in paleontology. He is best known for his work and research on theropoda, theropod dinosaurs and his detailed illustrations, both l ...
published a new reconstruction of the skeleton of ''B. brancai'', highlighting differences in proportion between it and ''B. altithorax''. Chief among them was a distinction in the way the trunk vertebrae vary: they are fairly uniform in length in the African material, but vary widely in ''B. altithorax''. Paul believed that the limb and girdle elements of both species were very similar, and therefore suggested they be separated not at genus, but only at subgenus
In biology, a subgenus ( subgenera) is a taxonomic rank directly below genus.
In the International Code of Zoological Nomenclature, a subgeneric name can be used independently or included in a species name, in parentheses, placed between the ge ...
level, as ''Brachiosaurus (Brachiosaurus) altithorax'' and ''Brachiosaurus (Giraffatitan) brancai''.[ ''Giraffatitan'' was raised to full genus level by George Olshevsky in 1991, while referring to the vertebral variation.][ Between 1991 and 2009, the name ''Giraffatitan'' was almost completely disregarded by other researchers.][
A detailed 2009 study by Taylor of all material, including the limb and girdle bones, found that there are significant divergences between ''B. altithorax'' and the Tendaguru material in all elements known from both species. Taylor found twenty-six distinct osteological (bone-based) characters, a larger difference than between ''Diplodocus'' and '' Barosaurus'', and therefore argued that the African material should indeed be placed in its own genus (''Giraffatitan'') as ''Giraffatitan brancai''.][ An important contrast between the two genera is their overall body shape, with ''Brachiosaurus'' having a 23 percent longer dorsal vertebral series and a 20 to 25 percent longer and also taller tail.][ The split was rejected by Daniel Chure in 2010,][ but from 2012 onward most studies recognized the name ''Giraffatitan''.]
Description
Size
Between 1914 and the 1990s, ''Giraffatitan'' was claimed to be the largest dinosaur known (ignoring the possibly larger but lost '' Maraapunisaurus'') and thus the largest land animal in history. In the later part of the twentieth century, several giant titanosaurians found appear to surpass ''Giraffatitan'' in terms of sheer mass. However, ''Giraffatitan'' and ''Brachiosaurus'' are still the largest sauropods known from relatively complete material.[
All size estimates for ''Giraffatitan'' are based on the skeleton mounted in Berlin, which is partly constructed from authentic bones. These were largely taken from specimen HMN SII,][ a subadult individual between in length and about tall.] The often mentioned length of 22.46 metres is by Werner Janensch, the German scientist who described ''Giraffatitan'', and was the result of an adding error: the correct number should have been 22.16 metres. Mass estimates are more problematic and historically have strongly varied from as little as to as much as . These extreme estimates are now considered unlikely due to flawed methodologies. There are also a large number of such estimations as the skeleton proved to be an irresistible subject for researchers wanting to test their new measuring methods. The first calculations were again made by Janensch. In 1935, he gave a volume of 32 m3 for specimen SII and of 25 m3 for specimen SI, a smaller individual. It is not known how he arrived at these numbers. In 1950, he mentioned a weight of forty tonnes for the larger skeleton. In 1962, Edwin Harris Colbert measured a volume of 86.953 m3. Presuming a density
Density (volumetric mass density or specific mass) is the ratio of a substance's mass to its volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' (or ''d'') can also be u ...
of 0.9, this resulted in a weight of 78,258 kilograms. Colbert had inserted a museum model, sold to the public, into sand and observed the volume displaced by it. Gregory S. Paul
Gregory Scott Paul (born December 24, 1954) is an American freelance researcher, author and illustrator who works in paleontology. He is best known for his work and research on theropoda, theropod dinosaurs and his detailed illustrations, both l ...
in 1988 assumed that the, in his opinion, unrealistically high number had been caused by the fact that such models used to be very bloated compared to the real build of the animal. In 1980, Dale Alan Russell ''et al'' published a much lower weight of 14.8 tonnes by extrapolating from the diameter of the humerus and the thighbone. In 1985, the same researcher arrived at 29 tonnes by extrapolating from the circumference of these bones. In 1985, Robert McNeill Alexander found a value of 46.6 tonnes inserting a toy model of the '' British Museum of Natural History'' into water.
More recent estimates based on models reconstructed from bone volume measurements, which take into account the extensive, weight-reducing airsac systems present in sauropods, and estimated muscle mass, are in the range of . In 1988, Gregory S. Paul measured a volume of 36.585 m3 by inserting a specially constructed model into water. He estimated a weight of 31.5 tonnes, assuming a low density. In 1994/1995 a weight of 40 tonnes extrapolating from limb bone circumference. In 1995 a laser scan of the skeleton was used to build a virtual model from simple geometrical shapes, finding a volume of 74.42 m3 and concluding to a weight of 63 tonnes. In 2008, Gunga revised the volume, using more complex shapes, to 47.9 m3. Donald Henderson in 2004 employed a computer model that calculated a volume of 32.398 m3 and a weight of 25,789 kilograms. Newer methods use bone wall thickness.
However, HMN SII is not the largest specimen known (an assertion supported by its subadult status) but HMN XV2, represented by a fibula 13% larger than the corresponding material on HMN SII, which might have attained in length.[Holtz, Thomas R. Jr. (2008) ''Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages']
Supplementary Information
/ref> Gregory S. Paul initially estimated the size of this specimen at in total length, in total height and in body mass, but later moderated at in total length and in body mass. In 2020, Molina-Perez and Larramnedi estimated the size of the HMN XV2 specimen at and , with a shoulder height of .
General build
''Giraffatitan'' was a sauropod, one of a group of four-legged, plant-eating dinosaurs with long neck
The neck is the part of the body in many vertebrates that connects the head to the torso. It supports the weight of the head and protects the nerves that transmit sensory and motor information between the brain and the rest of the body. Addition ...
s and tail
The tail is the elongated section at the rear end of a bilaterian animal's body; in general, the term refers to a distinct, flexible appendage extending backwards from the midline of the torso. In vertebrate animals that evolution, evolved to los ...
s. The estimated tail length makes up approximately 27.2% of the total body length. It had a giraffe
The giraffe is a large Fauna of Africa, African even-toed ungulate, hoofed mammal belonging to the genus ''Giraffa.'' It is the Largest mammals#Even-toed Ungulates (Artiodactyla), tallest living terrestrial animal and the largest ruminant on ...
-like build, with long forelimbs and a very long neck. The skull had a tall arch anterior
Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position pro ...
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
A claw is a curved, pointed appendage found at the end of a toe or finger in most amniotes (mammals, reptiles, birds). Some invertebrates such as beetles and spiders have somewhat similar fine, hooked structures at the end of the leg or Arthro ...
ed.
Skull
Traditionally, the distinctive high-crested skull was seen as a characteristic of the genus ''Brachiosaurus,'' to which ''Giraffatitan brancai'' was originally referred; however, it is possible that ''Brachiosaurus altithorax'' did not show this feature, since within the traditional ''Brachiosaurus'' material it is known only from Tanzanian specimens now assigned to ''Giraffatitan.''
The placement of ''Giraffatitan'' nostrils has been the source of much debate with Witmer (2001) describing in ''Science
Science is a systematic discipline that builds and organises knowledge in the form of testable hypotheses and predictions about the universe. Modern science is typically divided into twoor threemajor branches: the natural sciences, which stu ...
'' the hypothesized position of the fleshy nostrils in ''Giraffatitan'' in as many as five possible locations. Comparing the nares of dinosaurs with those of modern animals, he found that all species have their external nostril openings in the front, and that sauropods like ''Giraffatitan'' did not have nostrils on top of their heads, but near their snouts. There has also been the hypothesis of various sauropods, such as ''Giraffatitan'', possessing a trunk. The fact that there were no narrow-snouted sauropods (''Giraffatitan'' included) tends to discredit such a hypothesis. Stronger evidence for the absence of a trunk is found in the teeth wear of ''Giraffatitan'', which shows the kind of wear that would result from biting and tearing off of plant matter rather than purely grinding, which would be the result of having already ripped the leaves and branches off with a trunk.
Classification
When describing ''Brachiosaurus brancai'' and ''B. fraasi'' in 1914, Janensch observed that the unique elongation of the humerus was shared by all three ''Brachiosaurus'' species as well as the British ''Pelorosaurus
''Pelorosaurus'' ( ; meaning "monstrous lizard") is a genus of Titanosauriformes, titanosauriform sauropod dinosaur. Remains referred to ''Pelorosaurus'' date from the Early Cretaceous period, about 140–125 million years ago, and have been foun ...
''. He also noted this feature in '' Cetiosaurus'', where it was not as strongly pronounced as in ''Brachiosaurus'' and ''Pelorosaurus''.[ Janensch concluded that the four genera must have been closely related to each other, and in 1929 assigned them to a ]subfamily
In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end botanical subfamily names with "-oideae", and zo ...
Brachiosaurinae within the family Bothrosauropodidae.[
During the twentieth century, several sauropods were assigned to Brachiosauridae, including ''Astrodon'', '' Bothriospondylus'', ''Pelorosaurus'', '' Pleurocoelus'' and ''Ultrasauros''.] These assignments were often based on broad similarities rather than unambiguous synapomorphies, shared new traits, and most of these genera are currently regarded as dubious. In 1969, in a study by R.F. Kingham, ''B. altithorax'', ''B. brancai'' and ''B. atalaiensis'', along with many species now assigned to other genera, were placed in the genus '' Astrodon'', creating an ''Astrodon altithorax''. Kingham's views of brachiosaurid taxonomy have not been accepted by many other authors. Since the 1990s, computer-based cladistic
Cladistics ( ; from Ancient Greek 'branch') is an approach to biological classification in which organisms are categorized in groups ("clades") based on hypotheses of most recent common ancestry. The evidence for hypothesized relationships is ...
analyses allow for postulating detailed hypotheses on the relationships between species, by calculating those trees that require the fewest evolutionary changes and thus are the most likely to be correct. Such cladistic analyses have cast doubt on the validity of the Brachiosauridae. In 1993, Leonardo Salgado suggested that they were an unnatural group into which all kinds of unrelated sauropods had been combined. In 1997, he published an analysis in which species traditionally considered brachiosaurids were subsequent offshoots of the stem of a larger grouping, the Titanosauriformes, and not a separate branch of their own. This study also pointed out that ''B. altithorax'' and ''B. brancai'' did not have any synapomorphies, so that there was no evidence to assume they were particularly closely related.
Many cladistic analyses have since suggested that at least some genera can be assigned to the Brachiosauridae, and that this group is a basal branch within the Titanosauriformes.[ The exact status of each potential brachiosaurid varies from study to study. For example, a 2010 study by Chure and colleagues recognized '' Abydosaurus'' as a brachiosaurid together with ''Brachiosaurus'', which in this study included ''B. brancai''.] In 2009, Taylor noted multiple anatomical differences between the two ''Brachiosaurus'' species, and consequently moved ''B. brancai'' into its own genus, ''Giraffatitan''. In contrast to earlier studies, Taylor treated both genera as distinct units in a cladistic analysis, finding them to be sister group
In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree.
Definition
The expression is most easily illustrated by a cladogram:
Taxon A and ...
s. Another 2010 analysis focusing on possible Asian brachiosaurid material found a clade including ''Abydosaurus'', ''Brachiosaurus'', '' Cedarosaurus'', ''Giraffatitan'' and ''Paluxysaurus'', but not '' Qiaowanlong'', the putative Asian brachiosaurid. Several subsequent analyses have found ''Brachiosaurus'' and ''Giraffatitan'' not to be sister groups, but instead located at different positions on the evolutionary tree. A 2012 study by D'Emic placed ''Giraffatitan'' in a more basal position, in an earlier branch, than ''Brachiosaurus'', while a 2013 study by Philip Mannion and colleagues had it the other way around.
A 2012 study on titanosauriform sauropods by Michael D'Emic placed ''Giraffatitan'' as sister
A sister is a woman or a girl who shares parents or a parent with another individual; a female sibling. The male counterpart is a brother. Although the term typically refers to a familial relationship, it is sometimes used endearingly to ref ...
to a clade containing ''Brachiosaurus'' and a tritomy of '' Abydosaurus'', '' Cedarosaurus'' and '' Venenosaurus'' as shown in the cladogram
A cladogram (from Greek language, Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an Phylogenetic tree, evolutionary tree because it does not s ...
below:
In their 2024 description of '' Gandititan'', Han ''et al''. analyzed the phylogenetic relations of Macronaria, focusing on titanosauriform taxa. They recovered ''Giraffatitan'' as the sister taxon to '' Sonorasaurus'', similar to some previous analyses, in a clade also containing ''Brachiosaurus''. The results of their phylogenetic analyses are shown in the cladogram below:
Paleobiology
The nostril
A nostril (or naris , : nares ) is either of the two orifices of the nose. They enable the entry and exit of air and other gasses through the nasal cavities. In birds and mammals, they contain branched bones or cartilages called turbinates ...
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
Terrestrial animals are animals that live predominantly or entirely on land (e.g. cats, chickens, ants, most spiders), as compared with aquatic animals, which live predominantly or entirely in the water (e.g. fish, lobsters, octopuses), ...
. Studies have demonstrated that water pressure
Pressure (symbol: ''p'' or ''P'') is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled ''gage'' pressure)The preferred spelling varies by country and ev ...
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).
Brain
''Giraffatitan''s brain
The brain is an organ (biology), organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It consists of nervous tissue and is typically located in the head (cephalization), usually near organs for ...
measured about 300 cubic centimetre
A cubic centimetre (or cubic centimeter in US English) (SI unit symbol: cm3; non-SI abbreviations: cc and ccm) is a commonly used unit of volume that corresponds to the volume of a cube that measures 1 cm × 1 cm × 1 cm. One ...
s, which, like those of other sauropods, was small compared to its massive body size. A 2009 study calculated its Encephalization Quotient
Encephalization quotient (EQ), encephalization level (EL), or just encephalization is a relative brain size measure that is defined as the ratio between observed and predicted brain mass for an animal of a given size, based on nonlinear regre ...
(a rough estimate of possible intelligence) at a low 0.62 or 0.79, depending on the size estimate used. Like other sauropods, ''Giraffatitan'' has a sacral enlargement above the hip which some older sources misleadingly referred to as a "second brain". However, glycogen bodies are a more likely explanation.
Nostril function
The bony nasal openings of neosauropods like ''Giraffatitan'' were large and placed on the top of their skulls. Traditionally, the fleshy nostrils of sauropods were thought to have been placed likewise on top of the head, roughly at the rear of the bony nostril opening, because these animals were erroneously thought to have been amphibious, using their large nasal openings as snorkels when submerged. The American paleontologist Lawrence M. Witmer rejected this reconstruction in 2001, pointing out that all living vertebrate
Vertebrates () are animals with a vertebral column (backbone or spine), and a cranium, or skull. The vertebral column surrounds and protects the spinal cord, while the cranium protects the brain.
The vertebrates make up the subphylum Vertebra ...
land animals have their external fleshy nostrils placed at the front of the bony nostril. The fleshy nostrils of such sauropods would have been placed in an even more forward position, at the front of the narial fossa, the depression which extended far in front of the bony nostril toward the snout tip.
Czerkas speculated on the function of the peculiar brachiosaurid nose, and pointed out that there was no conclusive way to determine where the nostrils where located, unless a head with skin impressions was found. He suggested that the expanded nasal opening would have made room for tissue related to the animal's ability to smell, which would have helped smell proper vegetation. He also noted that in modern reptiles, the presence of bulbous, enlarged, and uplifted nasal bones can be correlated with fleshy horns and knobby protuberances, and that ''Brachiosaurus'' and other sauropods with large noses could have had ornamental nasal crests.
It has been proposed that sauropods, including ''Giraffatitan'', may have had proboscis
A proboscis () is an elongated appendage from the head of an animal, either a vertebrate or an invertebrate. In invertebrates, the term usually refers to tubular arthropod mouthparts, mouthparts used for feeding and sucking. In vertebrates, a pr ...
es (trunks) based on the position of the bony narial orifice, to increase their upward reach. Fabien Knoll and colleagues disputed this for '' Diplodocus'' and ''Camarasaurus'' in 2006, finding that the opening for the facial nerve
The facial nerve, also known as the seventh cranial nerve, cranial nerve VII, or simply CN VII, is a cranial nerve that emerges from the pons of the brainstem, controls the muscles of facial expression, and functions in the conveyance of ta ...
in the braincase was small. The facial nerve was thus not enlarged as in elephants, where it is involved in operating the sophisticated musculature of the proboscis. However, Knoll and colleagues also noted that the facial nerve for ''Giraffatitan'' was larger, and could therefore not discard the possibility of a proboscis in this genus.
Metabolism
If ''Giraffatitan'' was endothermic (warm-blooded
Warm-blooded is a term referring to animal species whose bodies maintain a temperature higher than that of their environment. In particular, homeothermic species (including birds and mammals) maintain a stable body temperature by regulating ...
), 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 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. Internal organs of these giant sauropods were probably enormous.
Paleoenvironment
''Giraffatitan'' lived in what is now Tanzania in the Late Jurassic
The Late Jurassic is the third Epoch (geology), epoch of the Jurassic Period, and it spans the geologic time scale, geologic time from 161.5 ± 1.0 to 143.1 ± 0.8 million years ago (Ma), which is preserved in Upper Jurassic stratum, strata.Owen ...
Tendaguru Formation. Since 2012, the boundary between the Kimmeridgian and Tithonian is dated at 152.1 million years ago.[Gradstein, F.M.; Ogg, J.G.; Schmitz, M.D. & Ogg, G.M., 2012, ''A Geologic Time Scale 2012'', Elsevier]
The Tendaguru ecosystem
An ecosystem (or ecological system) is a system formed by Organism, organisms in interaction with their Biophysical environment, environment. The Biotic material, biotic and abiotic components are linked together through nutrient cycles and en ...
primarily consisted of three types of environment: shallow, lagoon-like marine environments, tidal flats and low coastal environments; and vegetated inland environments. The marine environment existed above the fair weather wave base and behind siliciclastic and ooid barriers. It appeared to have had little change in salinity
Salinity () is the saltiness or amount of salt (chemistry), salt dissolved in a body of water, called saline water (see also soil salinity). It is usually measured in g/L or g/kg (grams of salt per liter/kilogram of water; the latter is dimensio ...
levels and experienced tides and storms. The coastal environments consisted of brackish coastal lakes, ponds and pools. These environments had little vegetation and were probably visited by herbivorous dinosaurs mostly during droughts. The well vegetated inlands were dominated by conifer
Conifers () are a group of conifer cone, cone-bearing Spermatophyte, seed plants, a subset of gymnosperms. Scientifically, they make up the phylum, division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a sin ...
s. Overall, the Late Jurassic Tendaguru climate was subtropical to tropical with seasonal rains and pronounced dry periods. During the Early Cretaceous
The Early Cretaceous (geochronology, geochronological name) or the Lower Cretaceous (chronostratigraphy, chronostratigraphic name) is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 143.1 ...
, the Tendaguru became more humid. The Tendaguru Beds are similar to the Morrison Formation of North America except in its marine interbeds.
''Giraffatitan'' would have coexisted with fellow sauropod
Sauropoda (), whose members are known as sauropods (; from '' sauro-'' + '' -pod'', 'lizard-footed'), is a clade of saurischian ('lizard-hipped') dinosaurs. Sauropods had very long necks, long tails, small heads (relative to the rest of their b ...
s like '' Dicraeosaurus hansemanni'' and ''D. sattleri'', '' Janenschia robusta'', '' Tendaguria'' ''tanzaniensis'' and '' Tornieria africanus''; ornithischians like '' Dysalotosaurus lettowvorbecki'' and '' Kentrosaurus aethiopicus''; the theropods " Allosaurus" ''tendagurensis'', " Ceratosaurus" ''roechlingi'', "Ceratosaurus" ''ingens,'' '' Elaphrosaurus bambergi'', '' Veterupristisaurus milneri'' and '' Ostafrikasaurus crassiserratus''; and the pterosaur
Pterosaurs are an extinct clade of flying reptiles in the order Pterosauria. They existed during most of the Mesozoic: from the Late Triassic to the end of the Cretaceous (228 million to 66 million years ago). Pterosaurs are the earli ...
'' Tendaguripterus recki''.[ Weishampel, David B.; et al. (2004). "Dinosaur distribution (Late Jurassic, Africa)." In: Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): ''The Dinosauria'', 2nd, Berkeley: University of California Press. p. 552. .][Barrett, P.M., Butler, R.J., Edwards, N.P., & Milner, A.R. Pterosaur distribution in time and space: an atlas. p61–107. in Flugsaurier: ''Pterosaur papers in honour of Peter Wellnhofer''. 2008. Hone, D.W.E., and Buffetaut, E. (eds). Zitteliana B, 28. 264p]
/ref> Other organisms that inhabited the Tendaguru included coral
Corals are colonial marine invertebrates within the subphylum Anthozoa of the phylum Cnidaria. They typically form compact Colony (biology), colonies of many identical individual polyp (zoology), polyps. Coral species include the important Coral ...
s, echinoderm
An echinoderm () is any animal of the phylum Echinodermata (), which includes starfish, brittle stars, sea urchins, sand dollars and sea cucumbers, as well as the sessile sea lilies or "stone lilies". While bilaterally symmetrical as ...
s, cephalopod
A cephalopod is any member of the molluscan Taxonomic rank, class Cephalopoda (Greek language, Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral symm ...
s, bivalve
Bivalvia () or bivalves, in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class (biology), class of aquatic animal, aquatic molluscs (marine and freshwater) that have laterally compressed soft bodies enclosed b ...
s, gastropod
Gastropods (), commonly known as slugs and snails, belong to a large Taxonomy (biology), taxonomic class of invertebrates within the phylum Mollusca called Gastropoda ().
This class comprises snails and slugs from saltwater, freshwater, and fro ...
s, decapods, sharks, neopterygian fish, crocodilians and small mammals like '' Brancatherulum tendagurensis''.
See also
* List of African dinosaurs
* Dinosaurs of Tendaguru
* Brachiosauridae
*Sauropoda
Sauropoda (), whose members are known as sauropods (; from ''wikt:sauro-, sauro-'' + ''wikt:-pod, -pod'', 'lizard-footed'), is a clade of saurischian ('lizard-hipped') dinosaurs. Sauropods had very long necks, long tails, small heads (relative t ...
* Sauropodomorpha
References
Bibliography
*Maier, Gerhard. 2003. ''African dinosaurs unearthed: the Tendaguru expeditions''. Life of the Past Series (ed. J. Farlow). Indiana University Press, Bloomington, Indiana
{{Taxonbar, from=Q14410
Brachiosauridae
Dinosaur genera
Tithonian dinosaurs
Tendaguru Formation
Taxa named by Gregory S. Paul
Fossil taxa described in 1988
Dinosaurs of Tanzania