Cambroraster falcatus was a radiodont that lived during the Cambrian, about 508-505 million years ago, in what is now western Canada. Part of the hurdiid family of radiodonts, it reached sizes of up to 30cm long (~12") – making it one of the largest animals known from the Burgess Shale fossil deposits.
Its distinctively-shaped massive head shield led to it being nicknamed "the spaceship" during collection and study of numerous fossil specimens. This was then referenced in its species name of "falcatus", inspired by its resemblance to the fictional Millennium Falcon from the Star Wars franchise.
Its short frontal appendages bore long curved spiny blades that formed a basket-like structure. Originally these were thought to be used to sift through seafloor sediment, but more recently they've been proposed as filter-feeding structures instead.
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References:
Moysiuk, Joseph, and J-B. Caron. "A new hurdiid radiodont from the Burgess Shale evinces the exploitation of Cambrian infaunal food sources." Proceedings of the Royal Society B: Biological Sciences 286.1908 (2019). https://doi.org/10.1098/rspb.2019.1079
Sun, Zhixin, Han Zeng, and Fangchen Zhao. "Occurrence of the hurdiid radiodont Cambroraster in the middle Cambrian (Wuliuan) Mantou Formation of North China." Journal of Paleontology 94.5 (2020): 881-886. https://doi.org/10.1017/S0016756820000187
Wikipedia contributors. “Cambroraster” Wikipedia, 27 Sep. 2025, https://en.wikipedia.org/wiki/Cambroraster
Mosura fentoni was a small radiodont living during the mid-Cambrian, about 508 million years ago, in near-equatorial shallow marine waters covering what is now western Canada.
Sixty specimens have been discovered in the Burgess Shale fossil deposits, ranging from 1.5cm long juveniles (~0.6") to 6cm long adults (~2.4"), giving us a detailed look at Mosura's anatomy and life history. It had three eyes – two on the sides of its head on short stalks and one in the middle of its face – and a pair of grasping frontal appendages each with six long sickle-shaped spines.
Unusually for a radiodont its body was divided into distinct regions: a four-segment neck, a six-segment mesotrunk with large swimming flaps, and an abdomen-like posterotrunk with up to at least sixteen segments (fewer in juveniles), all bearing gills along their undersides.
Its vaguely moth-like shape led to it being nicknamed "sea-moth" by field collectors, and inspired its genus name – "Mosura" is the Japanese name of the fictional giant kaiju moth-monster Mothra.
With a very high proportion of respiratory surface area for its size, Mosura was probably an active and agile fast-swimming predator, possibly living in low-oxygen waters around the outer continental shelf. Its wide oval central eye may have helped it stay orientated during rapid maneuvers, keeping track of the horizon line similar to the median eyes of modern dragonflies.
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NixIllustration.com | Tumblr | Patreon
References:
Moysiuk, Joseph, and Jean-Bernard Caron. "Early evolvability in arthropod tagmosis exemplified by a new radiodont from the Burgess Shale." Royal Society Open Science 12.5 (2025): 242122. https://doi.org/10.1098/rsos.242122
"Plate Tectonics and the Cambrian World" Royal Ontario Museum, https://burgess-shale.rom.on.ca/science/the-burgess-shale/geological-background/plate-tectonics-and-the-cambrian-world/
Royal Ontario Museum. "Palaeontologists discover 506-million-year-old predator" ScienceDaily, 13 May 2025, https://www.sciencedaily.com/releases/2025/05/250513225800.htm
Stange, Gert, et al. "Anisotropic imaging in the dragonfly median ocellus: a matched filter for horizon detection." Journal of Comparative Physiology A 188 (2002): 455-467. https://doi.org/10.1007/s00359-002-0317-7
Wikipedia contributors. “Mosura fentoni” Wikipedia, 19 May 2025, https://en.wikipedia.org/wiki/Mosura_fentoni
Paleontologists in China have uncovered exceptionally preserved fossils of a previously unknown genus and species of extinct arthropod, Kylinxia zhangi.
During the Cambrian explosion, a time full of incredibly weird-looking evolutionary experiments, Opabinia regalis was one of the weirdest of all – so ridiculous, in fact, that when its anatomy was first revealed at a presentation the audience laughed.
Known from the mid-Cambrian Burgess Shale fossil deposits in Canada, this bizarre creature lived around 508 million years ago and had a body measuring just 4-7cm long (~1.5-2.75").
It had five stalked eyes on its head, and a long flexible proboscis that resembled a vacuum cleaner hose ending in a pincer-like grasping structure. Its mouth was located on the bottom of its head, behind the base of its proboscis, and the opening pointed backwards forming a U-bend in its digestive tract.
The rest of its segmented body had overlapping swimming lobes and a tail fan, and small triangular structures that may have been legs on its underside.
It was probably a bottom-feeding predator or a detritvore, swimming along above the seafloor using its proboscis to snatch up small soft prey or organic material and passing it up to its mouth.
It also seems to have been a fairly rare member of the Burgess Shale ecosystem, with less than 50 specimens known from the thousands of fossils found there.
For a while Opabinia was thought to represent a completely new phylum, but after further discoveries of similar animals like Anomalocaris it's now considered to be a "stem-arthropod", a close evolutionary cousin to modern insects, arachnids, myriapods, and crustaceans. Its exact relationships with other stem-arthropods are still being debated, however, and some studies suggest its closest living relatives may actually be tardigrades.
