The biggest fish ever to live, and possibly one of the largest animals ever to live too.

Meaning of name: Leeds’ Fish

Species: Leedsichthys problematicus

Classification: Actinopterygii, Pachycormiformes, Pachycormiformidae.

Size: We’re actually unsure as to the true size of Leedsichthys, with estimates ranging from 13.5 metres (44.3 feet) to 27.6 metres (90.6 feet), with some popular science publications placing the animal between 30 and 35 metres (98-115 feet).

Weight: Estimates vary greatly, maxing out at roughly 40 metric tonnes (39.36 imperial tons).

Time: Calovian to Kimmeridgian stages of Jurassic Period.

Location: England, Germany, France and Chile.

Named by: Arthur Smith Woodward, in 1889.

Leedsichthys has always been steeped in controversy, particularly in relation to it’s size. At the start of the twentieth century, a length of 9 metres (29.5 feet) was shown to be possible, but by the twenty-first-century estimates ranged up to 30 metres (98 feet). Recent research, however, places the animal at a maximum size of about 16 metres (52.5 feet). In truth, we don’t actually know, we have only fragmentary evidence of its existence and each piece of evidence suggests a very different size to the last.

Was this beast prey for anything in the oceans of its time? I wouldn’t be surprised, seeing as it shared its time and waters with carnivores such as Mosasaurus and Liopleurodon (both of which were of almost equal size to Leedsichthys’ latest size estimates). Did it fear the mighty Megalodon, as Steve Alten has portrayed in his Meg books? No, the two species lived millions of years apart.

What we do know is that this giant (no matter its size) was a filter-feeder, feeding off of the plankton and phytoplankton drifting through the currents.



This has been Leedsichthys, this has been me, and you’ve been reading Dinosaurs Made Easy.


Image courtesy of: DK find out!


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