Do biologists know the first animal to have a heart (circulatory system) and a brain? Same animal?

Question

Do biologists know the first animal to have a heart (circulatory system) and a brain? Same animal?

Answer 1

The simplest form of circulatory systems and neural ganglia are found in invertebrates. The Cnidarians (jellyfish, hydra) are studied as the animals with basal forms of tissue and organ-like structures.

Earlier fossil records are lacking because soft tissue does not fossilize well so evidence is sought in creatures that show distinct types of tissue organization like jelly fish and worms that still exist. They have open non-circulating fluid movement and neural nets of cells able to conduct impulses that produce reflexive reactions in the organism.

http://www.unibas.ch/dib/zoologie/resear...

Answer 2

the could tell you what animals in the fossil record have hearts and brains first compared to others in the fossil record.

keep in mind that it would be an argument from ignorance to suggest that modern biology is false due to the inability to specifically point to one animal specifically.