The latent morphological space contains an ’Broadness vector’.

The beaks highlighted in the red box are generated from random latent vectors. The beaks on the right and left are after moving the latent vector along the broadness vector in the positive or negative direction respectively. The elongation vector was found by regressing the latent space against independent measurements of the length and width of the beaks in the observed dataset (see Methods for details). Note that the highlighted beaks are the same as those highlighted in Fig 2, but viewed from a different angle to make their degree of broadness easier to see.