The "ornithorynque" of the world of crab was an active predator who prowled in the seas of Cretaceous
Such a rare discovery is perplexed, a 95 million year old crab fossil discovered by the main author Javier LUQUE, postdoctoral researcher in the organism of the organism and evolution at Harvard, and entirely described in2019 in the journal advanced scientific.The fossil, found in a layer of rock of Cretaceous in the Andes of Colombia, presented a rare preservation of both external eye and internal optical tissue.In a new study, Luque and researchers from Yale describe the unusual optical characteristics of Calllightimer, which suggests that it was a very visual swimmer predator.
of Calllightère The eyes are one of its most unusual and striking characteristics due to their enormity.Living crabs generally have tiny compound eyes located at the end of a long stem with an orbit to cover and protect.Calllightère, however, has large eyes composed without orbits to protect them.The researchers first thought Calllightère was a crab at the last larval stage called megalope, which means big eyes.At this point, crabs have very big eyes; however, this is a brief moment in the development of crab.As the crab becomes a juvenile, the body becomes too large for the eyes.
To test this, Luque and the first author Kelsey Jenkins, doctoral student in Yale, analyzed more than 1,000 specimens of live and off crabs representing 15 species of crabs of the family tree of crabs.The specimens included crabs at different stages of development and encompassed a range of habitats, ecologies, lifestyles and Bathymetrical ranges.They measured the dimensions of the eyes and body of the crabe specimens from infant to adults and found that, unlike other crab species, Callightère has kept his big eyes throughout development.In reality, to call the eyes were the fastest growth of all species and could reach up to 16% of their whole body, about the size of a quarter.As a comparison, imagine a human with eyes the size of a football ball.
"Having such large and unprotected eyes implies that they were exposed at any time, and such large eyes impose a huge investment of energy and resources to maintain them.Thus, this animal had to count considerably on the vision, ”said Luque.
"If something has such big eyes, they are certainly very visual.This contrasts strongly with crabs with tiny and residual eyes where they can represent only 1 to 3% of the body size of the animal, "said Jenkins.
A further analysis has shown that Calllightimère was an animal with high visual acuity similar to dragonflies - which are among predators at the top of the world of insects - and a mantis shrimp.The remarkable conservation of the moon fabrics internal in the eyes of the Callichére, like the optical lobes (neural fabrics), shows that they looked more like the eyes of the bees and other insects with the big eyes than with the pedunculated eyes of the crabs.The animal was also more suitable for well -lit conditions.All the anatomical information available pointed to Calllightre to be a predator.
"Even if it is the cute and smallest crab, the big eyes of Calllightimer and its general shape with unusually large legs in the shape of a train indicate that it could have been a fierce swimmer predatory, rather than abackground robot as most of the crabs are, "said Luque.
"The crabs whose eyes develop very quickly are more visually tilted - they are probably very good predators who use their eyes during hunting - while slow growth eyes tend to be found in carognard crabs that depend lessVisually, ”said co -of -the teacher derek eg brigs, Yale.
de Calllightère The continuous surprise discoveries correspond to the translation of the name "Beautiful Perplexed Chimera"."I call it my beautiful nightmare because it took me more than a decade to visit museums around the world and analyze thousands of fossils and living crabs to understand how unique the animal was.It’s so confusing, so different from everything else, that it can be considered the ornithorynque of the crab world, "said Luque."The exceptional preservation of organisms with soft or slightly mineralized fabrics, such as eyes, allows us to have new glimpses of the history and evolution of life through deep time spectacularly.To give meaning to our present, we must look at our past, and for that, the data is in the strata.»»
The works were funded in part by the National Science Foundation (NSF, subsidy DEB #1856679), the National Council for Research in Science and Engineering of Canada (CRSNG), the Fondo Corrigan-ACGGP-ARES (Colombia) and the CommissionColombian geological, to the main author.
