But it did not take long for the fledgling land vertebrates to evolve greater sensory complexity.(dinosaur factory) Early in the Coal Age, quite large notches for eardrums appeared prominently in the skulls of the keyhole amphibians (loxommatids), a tribe of aggressive, sharply fanged predators with alligatorlike skulls. (“Keyhole” refers to the peculiar shape of their eye socket; an enlargement at the front of it may have housed a gland.) (lifelike dinosaur for sale)Keyhole amphibians clearly could hear airborne sounds, and therefore quite possibly used their voices to bluff and challenge and court. Since their heads reached a length of two and a half feet, they would surely have uttered a croak that would command respect. Other ear-equipped amphibians evolved after them as the Coal Age continued, so the spring mating season probably witnessed a diversified range of timbre and tone.
Reptile ears are built to the same general pattern as are amphibian ears, but the details of how the nerves pass through the auditory apparatus are different. Most paleontologists presently believe that reptiles evolved their ear independently and did not simply inherit their auditory machinery from amphibian ancestors. (big size dinosaur for sale)Today, the ears of lizards work much like the ears of frogs, but the ears of Coal Age reptiles are biosonic puzzles. A good notch for the eardrum evolved in some reptile tribes very early, yet the bone of the middle ear was thick and ponderous, not the delicate, thin bone absolutely required for hearing mid and high frequencies. Massive ear bones wouldn’t transmit most vibrations from the eardrum to the brain, and some of these early reptile ear bones are as big as a man’s thumb. What could these ancient reptiles have heard, if anything? It remains a mystery. (dinosaur costume)Some anatomists have suggested that the heavy ear bone was suspended by delicate ligaments and acted as a kind of seismograph for detecting very low-frequency sound. This suggestion evokes visions of a mating dance in which the courting couple stomps about producing minor earth tremors to communicate their lust. Reptiles did not evolve ears of high sensitivity until late in the Permian Period, long after the Coal Age, and the Reptilia certainly weren’t equipped to transmit and receive airborne melodies before then.