Tiktaalik roseae fossil. Photo used from Wikimedia Commons, uploaded by Eduard Solà.

 How did Tiktaalik roseae reproduce?

What enviornment did Tiktaalik need to reproduce?

Tiktaalik roseae played a key role in animals transitioning from life in the water to life on land. Tiktaalik likely had a simple form of lungs as well as gills and the ability to go onto land (Shipman, 2006).   However, it still had a huge tie to the water and was not evolved enough to live outside of it. Although Tiktaalik may have ventured onto land, a large majority of its life was spent in the water. This includes its birth and development stages of life (Clack, 2012). Much like modern day amphibians, Tiktaalik required water in order for it to reproduce.

How did Tiktaalik roseae reproduce?

Tiktaalik roseae mostly likely lived an amphibious life style and reproduced very similarly to amphibians. The life cycle starts with the female laying its eggs in the water. The male would then deposit a cloud of sperm over the eggs and fertilize them. The eggs would then develop into an aquatic larvae. This larvae most likely possessed external gills and spent its entire larval state in the water (Daeschler et al., 2006). At some point, the aquatic larvae would metomorphosis into the adult stage which would continue to grow to its full size.

How does the reproduction of Tiktaalik differ from amphibians?

At some point in the carboniferous period, a group of tetrapods developed an amphibous egg. This new style of egg was harder because of the presense of calcium carbonate. This allowed gases to exchange while keeping the egg impenetrable to water (Duellman, 1994). These amphibious eggs were not used by early tetrapods like Tiktaalik, but it evolved from Tiktaalik's life cycle. The other key difference in the two lie cycles is the presence of developmental stages. Modern amphibians developed stages inbetween the aquatic larval stage and the adult stage. Tiktaalik shows no evidence of developmental stages and likely metomorphosised straight into its adult form. Modern amphibians evolved stages of development from this life cycle. An example of a developmental stage is a tadpole in frogs.




What advantages did this type of reproduction have?

When Tiktaalik would lay its eggs, it would lay a large amount of small eggs. This favored the reproductive stratagy of producing many offspring and hoping that some survive. Tiktaalik would not care for its individual offspring because so many were laid. Instead after the eggs were laid, they would be left alone. Eggs could potentially be disturbed and never hatch. If the eggs are lucky enough to hatch, it was likely that many of the aquatic larvae would die (Duellman, 1994). Although many would die, the large number of eggs helped this life style to survive and evolve into life styles that we see today.

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