Vaderlimulus tricki
By Tas Dixon
Etymology: Darth Vader’s horseshoe crab
First Described By: Lerner et al, 2017
Classification: Biota, Archaea, Proteoarchaeota, Asgardarchaeota, Eukaryota, Neokaryota, Scotokaryota Opimoda, Podiata, Amorphea, Obazoa, Opisthokonta, Holozoa, Filozoa, Choanozoa, Animalia, Eumetazoa, Parahoxozoa, Bilateria, Nephrozoa, Protostomia, Arthropoda, Chelicerata, Xiphosura, Xiphosurida, Limulina, Austrolimulidae.
Status: Extinct
Time and Place: 251 to 247 million years ago, the Olenekian of the Early Triassic.
Vaderlimulus is only known from Idaho.
Physical Description: Vaderlimulus was similar in many respects to modern horseshoe crabs. They call them “living fossils” for a reason. The entire body (around 47 mm long not including the telson, which would have more than doubled total length) was protected by a hard carapace, with tiny eyes at the top of this. The legs were present on the underside, with a long, stiff telson projecting posteriorly. The most noteworthy feature of Vaderlimulus is the fact that the lateral spines of its carapace are highly splayed laterally and strongly curved backwards. Modern horseshoe crabs also have these spines, but they’re closely appressed to the body, giving the entire carapace a rounded appearance. You can probably guess why Vaderlimulus bears the name it does
Diet: Vaderlimulus presumably had a similar diet to modern horseshoe crabs, consisting of smaller seafloor invertebrates such as worms and shellfish. And sometimes algae.
Behavior: Presumably, Vaderlimulus had similar behavior to modern horseshoe crabs, feeding on the muddy bottom of shallow waters. Based on its close relatives such as Austrolimulus, Vaderlimulus may have even lived in freshwater. Whether it therefore underwent the same mass spawning as modern marine horseshoe crabs is unknown.
Ecosystem: The geological formation Vaderlimulus comes from is not good at preserving body fossils, but it is rich in trace fossils. Feeding traces and burrows of worms, resting traces of bivalves, and impressions left by fish in the sediment are known, as are impressions of cycads and bennettitales. At least one ammonite has also been preserved. These indicate that the environment was likely a coastal area.
Other: Vaderlimulus is one of the earliest records of the Dark Side in prehistory.
~ By Henry Thomas
Sources Under the Cut
