what is the history behind this dauphin?
Guigues IV, Count of Vienne, had a dolphin on his coat of arms and was nicknamed "le Dauphin". The title of Dauphin de Viennois descended in his family until 1349, when Humbert II sold his seigneury, called the Dauphiné, to King Philippe VI on condition that the heir of France assume the title of "le Dauphin".
Dauphin of France
Guigues IV, Count of Vienne, had a dolphin on his coat of arms and was nicknamed "le Dauphin". The title of Dauphin de Viennois descended in his family until 1349, when Humbert II sold his seigneury, called the Dauphiné, to King Philippe VI on condition that the heir of France assume the title of "le Dauphin". 
how old was the queen of scots when she died 44 years old ( 1542-1587). who is this queen? The Queen of Scots. which country did she rule? Scotland. how did she spend her childhood? She spent most of her childhood in France while Scotland was ruled by regents. who are these rulers mentioned last? It  is a person appointed to govern a state "pro tempore" because the regnant monarch is a minor, is absent, abdicated the throne, is incapacitated or dead, or inability to discharge the powers and duties of the monarchy. what did this aforesaid queen do in france? She married the Dauphin of France, Francis.
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Dauphin of France [SEP] History
Guigues IV, Count of Vienne, had a dolphin on his coat of arms and was nicknamed "le Dauphin". The title of Dauphin de Viennois descended in his family until 1349, when Humbert II sold his seigneury, called the Dauphiné, to King Philippe VI on condition that the heir of France assume the title of "le Dauphin". The wife of the Dauphin was known as "la Dauphine". The first French prince called "le Dauphin" was Charles the Wise, later to become Charles V of France. The title was roughly equivalent to the English (thence British) "Prince of Wales", the Scottish "Duke of Rothesay", the Portuguese "Prince of Brazil", the Brazilian "Prince of Grão-Pará" and the Spanish "Prince of Asturias".