The angry Minion-like anusless creature is not the earliest ancestor of mankind

A 2017 study concluded that an angry Minion-like microscopic creature without an anus was the earliest human ancestor.

However, new research has found that the spiky, wrinkled sack called Saccorhytus is in fact unrelated to humans.

Saccorhytus has pores around its mouth, which was first understood to be a primitive feature of the group of animals Deuterostomia (secondary oral animals) from which we emerged. However, analysis of 500-million-year-old fossils from China shows that these pores are in fact the basis of spines that broke apart during their preservation.

The team, led by scientists from the Nanjing Institute of Geology and Paleontology (China), placed Saccorhytus in another evolutionary group, related to arthropods such as spiders, crabs and insects.

All bilaterally symmetrical animals - one on the left and one on the right - are descendants of one of two distinct groups of protostomes (protozoa) and deuterostomes (secondary oral animals).

With protostomes, the mouth forms before the anus during embryonic development, but with deuterostomes it happens the other way around.

Bugs, crabs, and mussels all belong to the evolutionary lineage of protosomes, while vertebrates like humans come from deuterostomes.

Until the new discovery, published today in the journal Nature, it was thought that Saccorhytus was the earliest representative of the group Deuterostomia.

The fossil of this creature, about 1 mm in diameter, was first discovered in rocks in China's Shaanxi province in 2012 and described in 2017.

These fossils appear to have tympanic foramen around their mouths, leading to their identification as deuterostomes.

When they were 535 million years old, it was concluded that they were the earliest animals of that group.

But more recently, paleontologists have dug up more Saccorhytus specimens and recovered hundreds of better-preserved specimens.

Saccorhytus had pores around the mouth, first understood as gills - a primitive feature of the group of animals Deuterostomia from which humans emerged. Pictured is an artist's reconstruction of Saccorhytus coronarius

The team placed them in another evolutionary group, relating them to arthropods like spiders, crabs and insects. Pictured is an artist's reconstruction with a side (left) and back (right) view of Saccorhytus coronarius

Saccorhytus is said to look like an angry Minion from the cartoon Despicable Me

Yunhuan Liu, professor of paleontology at Chang'an University, Xi'an, China, said: 'Some fossils are so perfectly preserved that they look almost alive. Saccorhytus is a curious beast, with a mouth but no anus, with intricate rings of spines around its mouth'.

Hundreds of X-ray images were taken of a new fossil using a particle accelerator at Swiss Light Source in Switzerland to create a detailed 3D digital model. This suggests that the creature has spines around the mouth made by a degradable cuticle extending through the pores.

"We believe these will help Saccorhytus capture and process its prey," suggests Huaqiao Zhang from the Nanjing Institute of Geology and Paleontology.

Important: They are not gills, eliminating the only evidence that they are human-like deuterostomes.

Scientists have since hypothesized that Saccorhytus belongs to a group in Protosomia known as the ecdysoszoan, which contains arthropods and roundworms.

Professor Philip Donoghue from the University of Bristol (UK) said: 'We looked at a lot of alternative groups to which Saccorhytus might be related, including corals, anemones and jellyfish that also have mouths but no anus. To solve the problem, our computational analysis compared the anatomical structure of Saccorhytus with all other groups of living animals, concluding a relationship with arthropods and their relatives, the insect group, crabs and roundworms'.

Saccorhytus doesn't have an anus, which means any waste inside its body will return through its mouth. But Saccorhytus also makes up a fascinating piece of evolutionary history, suggesting that at some point this trait disappeared from its group.

As it is thought to be part of the group Deuterostomia, the vanishing anus contributes to our understanding of how modern vertebrate bodies were formed.

But now, this event is considered part of the history of ecdysozoa, whose intestinal tract extends from the mouth to the anus.

Shuhai Xiao from Virgina Tech (USA) said: 'Members of the Saccorhytus group show that it has evolved to have an evolutionary, anal distribution inherited from its ancestors'.

Ecdysozoa traditionally had worm-like bodies, so the sack-like Saccorhytus implies that the ancestors of the ecdysozoans may not have resembled worms.

"We still don't know the exact position of Saccorhytus in the tree of life, but it may reflect the ancestral status from which all members of this diverse group evolved," said Shuhai Xiao.

Further studies may involve examining the way Saccorhytus lived, for example floating in the sea or among grains of sand.

The researchers also wanted to determine exactly what they used the spikes for, such as deterring predators.

The search for the earliest human ancestors is still underway, now Saccorhytus is not considered part of Deuterostomia.

'The next oldest deuterostome fossil is nearly 20 million years younger,' said Shuhai Xiao.

Protostomes have a fossil record dating back 550 million years, but deuterostomes are only estimated to be 515 million years old.

Shuhai Xiao added: 'This means there is a big gap in the fossil record of deuterostomes. So we will continue to dig and find the first true deuterostome fossils."