How do you abbreviate ‘figure’ and ‘figures’ when used in a scientific paper?
In general, the rule is that when an abbreviation ends with the same letter as the word written out in full, a period (full stop) is not used. For example, Dr. Smith, but Drs Dupont and Dupond. However, in the case of Figures, both Fig., Figs., and Figs are acceptable and used. Therefore, you should follow the example used in the journal, i.e., check the formatting guidelines or look at other articles published recently in that journal. If in doubt, choose one style and use it consistently!
P.S. Perhaps a more day-to-day example is that (in British English) we write Mr Smith and Mrs Jones as opposed to Mr. Smith and Mrs. Jones because both of these words end with the same letter as the abbreviated form; that is, Mister and Mistress. However, in American English, a period is used after both Mr. and Mrs., so perhaps the most important lesson is that consistency and clarity are the most important factors.