pterosaur: an extinct reptile of the Jurassic and Cretaceous having a bird-like beak and membranous wings supported by the very long fourth digit of each forelimb
chordate: any animal of the phylum Chordata having a notochord or spinal column
trabecula: rod-shaped structures of fibrous tissue that divide an organ into parts (as in the penis) or stabilize the structure of an organ (as in the spleen)