অর্ডোভিশিয়ান যুগের ঠিক পরের যুগের নাম কী ?
A plethora of processes can be seen. "Arandaspis" is one of the oldest armored vertebrates ("herdocham") fossils from the Middle Ordovician. Ordovician-era trilobites differed greatly from their earlier Cambrian cousins. Many of their species have the advantage of protecting themselves from the attacks of predators such as primitive eurypterids, nautiloids, etc. through the evolution of spines and knobs of various shapes. Species like "Aglina pisca" develop suitable swimming morphology. Shovel-like proboscis reappears in the mouth of some trichandas to collect food from the mud of the sea floor. A little-known relative of trinuclides, called trinuclides, evolved a broad border around their helmets. "Assaphus kowalewski" etc. are predators on the head of some Trikhandi
Silurian Period