A fascinating new species of arachnid from the late Carboniferous is introduced in a new … [+]
Many people harbor the false belief that most of the world’s animals have already been discovered. But that is not the case. By some estimates, as many as seven million species remain to be named. Given that approximately 1.5 million species have been formally documented to science, that leaves 80% or more waiting to be discovered.
When we start talking about historical species, the number becomes even greater.
So it should come as no surprise that a research team found a new species of arachnid – dating to the late Carboniferous period (about 300 million years ago) – in the fossil beds of Mazon Creek in northern Illinois. They recently published their discovery in the Journal of Paleontology.
“The Mazon Creek Fossil-Lagerstätte is justly famous for the abundance of marine and non-marine fossil biota found in clay-ironstone concretions collected from the cairns of the old strip mines around Braidwood in northeastern Illinois,” the authors said . by Paul Selden of the University of Kansas.
Fossils of many extant and extinct groups of arachnids have been found in Mazon Creek in the past. What’s surprising about the new discovery, however, is how morphologically unique this spider is.
“The new fossil from Mazon Creek is clearly quite different from any previously described arachnid from this or any other Coal Measures site,” the authors say. “It is characterized by its characteristic habit: an oval body and robust and very spiny legs. The preserved character combination makes it difficult to place the fossil in a known order of arachnids.”
A drawing of what the new fossilized species, Douglassarachne acanthopod, actually looked like … [+]
The authors believe that the spines on each of the spider’s eight legs evolved as a defense against predators. They point to spininess in other late Carboniferous arthropods, such as trigonotarbids and millipedes, which lacked spines in their earlier relatives, as evidence that spines were an adaptation unique to this period in history.
They also note the similarity to some living arachnids – including several species of armored harvestmen – which are also believed to exhibit spininess on their legs and bodies as a measure of protection against predators.
And while we can only imagine what this fossilized spider might have looked like in real life, we can look to some living “spiny spiders” for clues about its morphology and characteristics. Here are two:
1. Green Lynx Spider
A green lynx spider, Peucetia viridans, sits on a leaf at night in Belize.
The green lynx spider has a vibrant green hue and is usually seen among green foliage. This arachnid, the largest member of the Oxyopidae family, is found in the southern United States, Mexico, Central America, and several islands in the West Indies, especially Jamaica.
Lynx spiders are well-adapted hunters. They eschew the use of webs to capture their prey and instead employ a cat-like hunting technique, pouncing on unsuspecting victims. This behavior earns them their name: ‘lynx spiders’.
These spiders are active during the day and exhibit different physical characteristics. Females can reach lengths of up to 1 inch (2.5 cm), while males, which are more slender in build, typically measure about 1 inch (2.5 cm) in length. Their legs, ranging from green to yellow, are decorated with long black spines, a common feature in Oxyopidae species, alternating with dark spots.
2. Spiky Orb-Weaver
Spiny orb weavers are generally docile spiders, only biting when they feel threatened.
The spiny orb weaver spider, true to its name, has a round abdomen decorated with numerous spines, resembling the shape of a crab’s shell. These spines, often brightly colored in shades of white, yellow, red or black, serve as both a form of protection and a visual deterrent against potential predators.
This species is found primarily in tropical and subtropical regions around the world, including parts of North and South America, Africa and Asia, and has attracted attention for its striking morphology. In addition to its striking physical characteristics, the spiny orb weaver spider is known for its adeptness at constructing intricate orb webs, which it uses to capture prey. These webs, carefully woven with silk threads, have a characteristic spiral pattern radiating from the center, where the spider patiently awaits its next meal.
The spiny orb weaver is a small spider, typically five to nine millimeters long for females and slightly smaller for males. Their bites are not dangerous to humans.