Figures: Origins of a Stem Hero

Brower and Veinus

Image credit: Brower & Veinus 1974.

Millions of years before Peter Parker, the stem hero Eurypterid Man came into glorious being, only to meet an immediate tragic end.

 

About This Image

What on earth is this figure doing in a scientific paper?  And what does it mean?!?

This figure, appearing in the journal Mathematical Geology, is a playful visual metaphor for two different statistical approaches to analyzing complex data sets.  The statistical zap utilizes a single, targeted method of analysis that goes “straight to the heart” to reveal the underlying structure within a data set, but has the distinct potential of missing the mark entirely and yielding no useful information.  Instead, the authors advocate a multivariate shotgun approach that “literally overwhelms the target data and blasts it into oblivion.”  Brower and Veinus used the example of ontogenetic changes in a species of eurypterid, demonstrating that as the animal grows, it not only grows in overall size, but the relationship between different proportions and structures (e.g., eyes) changes in biologically relevant ways.  Such subtlety can be gleaned from the data using the shotgun approach.

Eurypterids are a group of extinct aquatic arthropods that are known to have existed from the Middle Ordovician (~460 mya) to the Permian (~260 mya).  These sleek predators are casually called “sea scorpions,” despite only a distant relationship with true modern scorpions.  Eurypterids belong to a larger group called Chelicerata, which includes arthropods such as horseshoe crabs, daddy longlegs (harvestmen), mites, scorpions, and spiders.  Since eurypterids are an extinct group within Chelicerates with no living descendants, they are a stem group.

The zapped and shotgunned eurypterid cartoon is no Marvel Comic, but  “. . . the senior author acknowledges son Jeffrey for the loan of his comic book collection in connection with [this figure].”

Special thanks to James Lamsdell for suggesting and providing this figure.

Image Source

Brower, James C. & J. Veinus.  1974.  “The Statistical Zap versus the Shotgun Approach.”  Mathematical Geology 6 (4):  311 – 332.

References

Lamsdell, James C. et al.  2015.  “The oldest described eurypterid:  a giant Middle Ordovician (Darriwilian) megalograptid from the Winneshiek Lagerstätte of Iowa.”  BMC Evolutionary Biology 15:  169.

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