with the first pairs longer and slightly curved

Medidas aproximadas del Yangchuanosaurus:

Tiktaalik roseae is a fossil vertebrate from the Late Devonian (approximately 375 million years ago) that represents a morphological and functional intermediate form between lobe-finned fish and the first limbed vertebrates (tetrapods)

siendo su rasgo más característico la vela o aleta dorsal que podía alcanzar los 2 metros y pudiera haberle servido de regulador térmico

Altirhinus kurzanovi Machairoceratops with the first pairs longerAltirhinus kurzanovi was an ornithopod dinosaur from the Early Cretaceous, about 120 million years ago, whose fossils have been found in the Khuren Dukh Formation (Mongolia). Its name means "high nose," alluding to its characteristic prominent, arched nasal protuberance. This trait is thought to have been related to vocal resonance, intraspecific recognition, or even visual display. Biometrically, Altirhinus reached between 6 and 8 meters in length ,