The protostome developmental sequence arose just once in evolutionary history, resulting in two main subgroups—Lophotrochozoa and Ecdysozoa. What does this finding most likely suggest?

It is true that the protostome developmental sequence arose just once in evolutionary history.

Explanation:

During evolution the Bilateria had been into two major divisions. One was the protostomes and another was the deuterostomes. It is all categorized during the embryonic development.  

It is differentiated by the formation of anus and mouth. The protostomes include the annelids, molluscs and arthropods. Studies reveal that Protostomes are derived from their prebilaterian ancestors.

The protostome developmental sequence has been aroused only once during evolution which lead to the evolution of more than thousands of new species. They then were subdivided into two major group, namely Lophotrochozoa and Ecdysozoa.

john maynard keynes developed new economic theories in response to the stock market crash of 1929. great depression of the 1930s. first and second world wars. economic boom of the 1950s.

for the united states of america, 1945 to 1964 was a time of high economic growth and general prosperity. it was also a time of confrontation as the capitalist united states and its allies politically opposed the soviet union and other communist countries; the cold war had begun.

explanation: