Dreadnoughtus

Dreadnoughtus Temporal range: Late Cretaceous, 84–66 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Skeletal restoration showing known elements
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Dinosauria
Clade:	Saurischia
Clade:	†Sauropodomorpha
Clade:	†Sauropoda
Clade:	†Titanosauria
Clade:	†Lithostrotia
Genus:	†Dreadnoughtus Lacovara et al., 2014
Species:	†D. schrani
Binomial name
Dreadnoughtus schrani Lacovara et al., 2014

Dreadnoughtus is a genus of giant titanosaurian dinosaur. Its fossilised skeleton was found in the Upper Cretaceous of Santa Cruz province, Argentina. These rocks date from 84–66 million years ago (mya).

This is one of the largest of all known terrestrial vertebrates. It has the greatest mass (weight) of any land animal that has been calculated. They used using limb bone measurements for the calculation.

Dreadnoughtus schrani is the most complete skeleton of a large titanosaurian sauropod dinosaur. Types of bones is the most important statistic. The completeness statistics for Dreadnoughtus schrani are as follows:

• 116 bones out of ~256 in the entire skeleton (including the skull) = 45.3% complete
• 115 bones out of ~196 in the skeleton (excluding the skull) = 58.7% complete
• 100 types of bones out of ~142 types in the skeleton (excluding the skull) = 70.4% complete

The specimen was probably not fully grown at the time of its death. The histology of its humerus, shows a lack of an outer layer of bone found only in fully-grown vertebrates. There is a lot of fast-deposited or still-growing bone tissue. Therefore, the specimen was still growing at the time of its death. It is unknown how large this individual would have grown if it had lived a full life.

Estimates

As a matter of basic science, the estimates of dimensions such as the mass (weight) of extinct animals are very rough figures. To avoid the pretence of spurious accuracy. we only give rounded figures here. Moreover. all the skeletons are incomplete, which means that even length (the easiest dimension to estimate) cannot be given exactly. Published estimates by scientists are just that: estimates. Estimation is an approximation given when information is not clear or is incomplete. It is like making an educated guess.

It is usual for estimates of mass (weight) to vary between experts. Using the same basic data, the weight of Dreadnoughtus has been estimated as:

1. About 59.3 metric tons (65.4 short tons), or 59,291 kilograms.
2. Between 35 and 40 metric tons (39 to 44 short tons),
3. About 30 metric tons (33 short tons), based on a 20% shorter torso.

There is a ~x2 difference between the heaviest and lightest estimates, and that is not at all unusual for this type of calculation.

Size

Dreadnoughtus dimensions

Dimension	metric	imperial
Mass	59,300 kilograms (59.3 t)	65.4 short tons (130,800 lb)
Total length	26 m	85 ft
Head and neck length	12.2 m	40 ft
Neck-only length	11.3 m	37 ft
Torso and hip length	5.1 m	17 ft
Tail length	8.7 m	29 ft
Shoulder height	~ 2 stories (6 m)	~ 2 stories (20 ft)

Comparisons

Sauropod	Group	metric tons	short tons
Dreadnoughtus schrani	Titanosauria	59.3	65.4
Brachiosaurus altithorax	Brachiosauridae	56.3	62.1
Turiasaurus riodevensis	Turiasauria	50.9	56.1
Elaltitan lilloi	Titanosauria	42.8	47.2
Futalognkosaurus dukei	Titanosauria	38.1	42
Giraffatitan brancai	Brachiosauridae	34	37.5
Diplodocus longus	Diplodocidae	14.8	16.3