4- The pycnogonid crown group (=Pantopoda) preceeds the appearance of the first pantopod fossil by ~206.5 Ma. Why this hole in the fossil record? Sea spiders have fragile, low-fossilization bodies and likely lived in environments unsuitable for fossil preservation. #FossilRecord #Paleontology

2- We found out that Pycnogonida diverged from the rest of the chelicerates during the Cambrian (~539-510 million years ago) while modern sea spiders (order: Pantopoda) took another 100 million years and appeared between the Silurian and the Devonian (~435-367 mya). #CambrianExplosion