Alcuni passaggi evolutivi dai Pesci agli Anfibi.

1. Tiktaalik roseae
Costole
Narici
Collo

5. Dopo il Tiktaalik…..

6. 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.

7. Periodo: 365m.a.
circa 50 cm

8. Dendrerpeton acadianum
Lunghezza: quasi 1m
300 000 000 m.a.
Carbonifero sup.
Nuova Scozia (Canada),
giacimento di Joggins.

9. 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.”
Joggins-LifeintheCarboniferous"
BrianChoo

10. Eryops megacephalus
280 m.a. Anfibio ?
come facciamo a saperlo??
Predatore

11. Vecchie
ingenuità

12. E prima del Tiktaalik??

13. 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.

14. 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.