The word Pinigrada is misspelled against Pinnigrada, a noun meaning "Same as Pinnipedia."
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Pinnigrada has double "nn" is mispronounced as "n"
Remember double 'NN' in between the strings pi & igrada which should not be misspelled with single 'N'
Wrong Spelling:  pi-n-igrada 
Correct Spelling:  pi-nn-igrada 
Find more wrongly spelled words of Pinnigrada to spell it well.