Pythias of Aso was a Greek biologist and embryologist, wife of Aristotle. It is believed that she collaborated with him in embryological studies and in the elaboration of an encyclopaedia, although the degree of collaboration between her and Aristotle is not known for certain. 

In this activity we propose to look at the evolution of the embryos of five vertebrate species and appreciate the change that occurs between them through the different stages of their development.

COMPARE VERTEBRATE EMBRYOS

1.- In the following image the first stages of embryo development of 5 vertebrate species are represented:

Describes similar characteristics between embryos: 

2.-Next, we have another image showing the same five embryos, but in later stages. Observe:

Do you notice any differences and do you dare to guess which animal species they belong to? 
 

3.- Finally, we show you in the following image the 5 foetuses belonging to the previous embryos:

Identify the clues to guess which animals they belong to: 
 
 
4. Finally, tell which species each of the five embryos shown belongs to:
a. __________________________________ 
b. __________________________________ 
c. __________________________________ 
d. __________________________________ 
e. __________________________________ 
 
5. Look up information on biogenetic law and explain it below: 
 
 
6. Find the meaning of the following concepts: 
   a) Ontogeny 
   b) Phylogeny