Tiktaalik roseae

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Dopo il Tiktaalik…..

Ichthyostega (Greek: "fish roof") is an early tetrapod that lived at 374 – 359 million years ago; it possessed lungs and limbs that helped it navigate through shallow water in swamps. Though undoubtedly of amphibian build and habit, Ichthyostegais not considered a true member of the group in the narrow sense. Until finds of other early tetrapods and closely related fishes in the late 20th century, Ichthyostega stood alone as the transitional fossil between fish and tetrapods, combining a fishlike tail and gills with an amphibian skull and limbs.

Periodo: 365m.a.circa 50 cm

Dendrerpeton acadianumLunghezza: quasi 1m

300 000 000 m.a.Carbonifero sup.

Nuova Scozia (Canada), giacimento di Joggins.

A representation of the fauna of Canada’s World Heritage Joggins Fossil Cliffs. Dendrerpeton chases a pair of early reptiles (Hylonomus) up a lycopod tree. The little microsaurian amphibian Asaphestera scuttles into the undergrowth. Behind them, the giant millipede-like arthropod Arthropleura forages unconcerned.”

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Eryops megacephalus

280 m.a. Anfibio ?come facciamo a saperlo??Predatore

Vecchie ingenuità

E prima del Tiktaalik??

Anatomically, Eusthenopteron shares many unique features in common with the earliest known tetrapods. Largest individuals grew up to 1.8 m (6.5 ft) in length. It shares a similar pattern of skull roofing bones with forms such as Ichthyostega and Acanthostega.

Eusthenopteron, had internal nostrils, (or a choana) which are found only in land animals and sarcopterygians. It also had labyrinthodont teeth, characterized by infolded enamel, which characterizes all of the earliest known tetrapods as well. Similarly, its elasmoid scales lack superficial odontodes composed of dentine and enamel; this loss appears to be a synapomorphy with more crownward tetrapodomorphs.

Eusthenopteron's notoriety comes from the pattern of its fin endoskeleton, which bears a distinct humerus, ulna, and radius (in the fore-fin) and femur, tibia, and fibula (in the pelvic fin). These appendicular long bones had epiphyseal growth plates that allowed substantial longitudinal growth through endochondral ossification, as in tetrapod long bones.