Largest land animal ever

Giant herbivorous sauropod dinosaurs (Sauropoda) of the Late Jurassic (161.5–145 million years ago) and Late Cretaceous (100.5–66 million years ago) periods are by far the largest animals ever to live on land. Based on fossilized remains, which admittedly present challenges owing to their fragmentary nature that often necessitates having to extrapolate full-body size and form, conservative estimates suggest that these gargantuan reptiles reached between 30 and 40 m (98–131 ft) long and weighed at least 50–75 tonnes (55–83 tons). A subset of the sauropods known as the titanosaurs (Titanosauria) – which included species such as Argentinosaurus, Patagotitan and Brukathkayosaurus – are likely to have surpassed the mass of other members of the family owing to a more bulky body shape. Indeed, a study published in the journal Lethaia in June 2023 theorized, albeit tentatively, that so called “super sauropods”, such as Brukathkayosaurus, may have even weighed in the range of 110–170 tonnes (121–187 tons), comparable to modern blue whales.

The heaviest land animals today are African bush elephants (Loxodonta africana), adult males of which can attain weights of 4–7 tonnes (4.4–7.7 tons). Today’s tallest terrestrial animal, meanwhile, is the giraffe (Camelopardis), adult males of which can reach 5.5 m (18 ft) from hoof to ossicones (furry horns).

The largest and heaviest animal ever is the extant blue whale (Balaenoptera musculus), which on average grows to 25 m (82 ft) long and weighs around 160 tonnes (176 tons). The heaviest specimen ever was a female caught in the Southern Ocean on 20 March 1947 that weighed 190 tonnes (209 tons) and measured 27.6 m (90 ft 6 in) in length. An even longer example was a female landed in 1909 at the whaling station in Grytviken in South Georgia in the South Atlantic, which was documented as measuring "107 fot". Based on the Norwegian fot (or “fod”) being equivalent to 313.74 mm (as of 1824), this gives a length of 33.57 m (110 ft 1.6 in).

Invertebrates can reach significantly greater lengths. The longest single animal is believed to be the bootlace worm (Lineus longissimus), a species of nemertean or ribbon worm, inhabiting shallow waters of the North Sea. In 1864, following a severe storm at St Andrews in Fife, UK, a 55-m-long (180-ft) specimen was washed ashore.