A filter-feeding 'lobster ' as big as a human took the place of whales 480 million years ago , a new fossil find has shown . The 6.5ft ( two-metre ) prehistoric creature belonged to the family of anomalocaridids that were the early ancestors of modern crustaceans , insects and spiders . At this length it would have been comparable in size to athlete Usain Bolt , actor Liam Hemsworth and former wrestler Hulk Hogan . A giant filter-feeding 'lobster ' ( illustrated left ) took the place of whales 480 million years ago , a new fossil find has shown . The 6.5ft ( two-metre ) prehistoric creature was an early ancestors of modern crustaceans , insects and spiders and at this length would have been comparable in size to athlete Usain Bolt ( pictured right ) The remains were unearthed in Morocco and it is thought to be the oldest giant filter-feeder ever discovered . But while most of its relatives were shark-like apex predators with circular mouths ringed by sharp teeth , the new species , named Aegirocassis benmoulae , was a 'gentle giant ' . The 6.5ft ( two-metre ) prehistoric creature belonged to the family of anomalocaridids that were the early ancestors of modern crustaceans , insects and spiders . Like modern-day whales , it filtered seawater to trap tiny particles of food , using spine-covered 'limbs ' on its head . Fossils also show that Aegirocassis had pairs of swimming flaps along its body . These were likely to be precursors of the unique double-branched appendages seen in modern crustaceans . Like modern-day whales , it filtered seawater to trap tiny particles of food , using spine-covered 'limbs ' on its head . Modern-day lobsters grow to around 19 inches ( 50cm ) and modern-day whales average at around 79ft ( 25 metres ) . Dr Allison Daley , from Oxford University , who co-led a team studying Aegirocassis writing in the journal Nature , said : 'This would have been one of the largest animals alive at the time . 'These animals are filling an ecological role that had n't previously been filled by any other animal . 'While filter-feeding is probably one of the oldest ways for animals to find food , previous filter-feeders were smaller , and usually attached to the sea-floor . 'We have found the oldest example of gigantism in a freely swimming filter-feeder . ' A. benmoulae was named after the Moroccan fossil hunter who discovered it , Mohamed Ben Moula . The 3D fossil , exposed using tiny needle-like tools to chip away the surrounding rock , is exceptionally well preserved . A. benmoulae was named after the Moroccan fossil hunter who discovered it , Mohamed Ben Moula . The three-dimensional fossil ( pictured ) , exposed using tiny needle-like tools to chip away the surrounding rock , is 'exceptionally well preserved ' . Other anomalocaridid fossils have been flat , like pressed leaves . The fossils ( pictured left and right ) also show that Aegirocassis had pairs of swimming flaps along its body , which were likely to be precursors to the unique double-branched appendages seen in modern crustaceans . They also bear resemblance to gill flaps seen on the trunks of modern arthropods . Dr Allison Daley , from Oxford University said : 'This would have been one of the largest animals alive at the time . While filter-feeding is probably one of the oldest ways for animals to find food , previous filter-feeders were smaller , and usually attached to the sea-floor . ' The fossil 's individual parts are annotated above . In contrast , other anomalocaridid fossils have been flat , like pressed leaves . 'Without these 3D remains we may never have got the insight into these animals ' anatomy that we did , ' said Dr Daley . The fossil shows that Aegirocassis had pairs of swimming flaps along its body , which were likely to be precursors of the unique double-branched appendages seen in modern crustaceans . They also bear resemblance to gill flaps seen on the trunks of modern arthropods . The large size of this filter feeder suggests that the anomalocaridids were well-adapted to take advantage of a presumably rich source of plankton during the Ordovician period , said the authors . The fossils were found in the Fezouata Biota formation region of central Anti-Atlas in Morocco ( marked ) Modern lobsters ( stock image ) grow to around 19 in ( 50cm ) and modern whales average at 79ft ( 25 metres )
Remains of the two-metre ( 6.5ft ) prehistoric creature unearthed in plankton . It lived 480 million years ago and belonged to the family of anomalocaridids . These were early ancestors of modern crustaceans , insects and spiders . Like modern-day whales , it filtered seawater to trap tiny particles of food . Fossils suggest it caught food using spine-covered 'limbs ' on its head . And experts claim it is the oldest giant filter-feeder ever discovered .