Lacosteaster
Extinct twelve-armed sea star from Miocene France.
**Lacosteaster** (meaning "Lacoste star") is an extinct genus of sea star belonging to the family Solasteridae. Its fossils come from the Early Miocene Calcaire de Ménerbes Formation in France. The genus contains just one species, *Lacosteaster lauerorum*, which is known from several well-preserved specimens. Its most distinctive feature is a set of twelve arms radiating from a relatively small central disc.
The first fossil material of this sea star was probably found in the Soubeyran quarry, near the village of Ménerbes in southeastern France, in rocks of the Lacoste plateau. Because the specimen was purchased after discovery, the exact find site is unknown. This nearly complete individual is preserved with its mouth-facing side upward on a limestone slab that also holds six fossils of the sea urchin *Tripneustes*. It is housed at the Lauer Foundation in Illinois, United States, as specimen LF 4905. In 2024, researchers Andrew S. Gale and David J. Ward named it as the holotype of a new genus and species. The genus name combines "Lacoste" (the type locality) with the Latin *aster* ("star"), a common suffix for sea star genera. The species name honors Bruce and René Lauer, founders of the Lauer Foundation. *Lacosteaster* is only the second fossil solasterid ever described, after *Plesiosolaster moretonis* from the Middle Jurassic of the United Kingdom.
In 2026, Anaïs Travers and colleagues described twelve additional *Lacosteaster* specimens from the same formation, now housed at the Musée des Confluences in Lyon, France. Eight came from the Soubeyran quarry; the other four have unknown origins. None are complete—eight preserve only arm fragments. Five are preserved with the mouth side up (like the holotype), four with the opposite side up, and three show both sides.
The body of *Lacosteaster* has a small central disc and twelve arms that taper sharply in the last third. In the holotype, each arm is about 18 centimeters long and bears several rows of small, tightly packed spines. The ratio of the large radius (disc center to arm tip) to the small radius (disc center to the area between arms) is 4.5 to 1. In other specimens, the large radius ranges from 10 to 17 centimeters. The mouth margin is lined with small conical spines.
The Calcaire de Ménerbes Formation dates to the late Burdigalian stage of the early Miocene, about 16 million years ago.
Quick Facts
- Genus
- Lacosteaster
- Species
- lauerorum
Facts from the source article.
Lore & Background
The first described Lacosteaster fossil material was likely discovered in the Soubeyran quarry, representing outcrops of the Calcaire de Ménerbes Formation near the village of Ménerbes in southeastern France. Since this specimen was purchased after its discovery, the exact discovery locality is unknown. The known individual is well-preserved and nearly complete, preserved with the actinal face up on a limestone slab that also preserves six fossil specimens of Tripneustes. In 2024, Andrew S. Gale and David J. Ward described Lacosteaster lauerorum as a new genus and species, establishing LF 4905 as the holotype. The generic name combines a reference to the type locality in Lacoste with the Latin aster, meaning 'star'. The specific name honors Bruce and René Lauer, founders of the Lauer Foundation. In 2026, Anaïs Travers and colleagues published on twelve new specimens of Lacosteaster, now accessioned in the Musée des Confluences in Lyon, France; eight were collected from the Soubeyran quarry, while the locality of the remaining four is unknown.
Reader's Guide
Lacosteaster is significant as part of a diverse assemblage of sea stars from the Calcaire de Ménerbes Formation, which also includes Astropecten, Cruciformaster, and Menerbesaster, each from a different family. This assemblage represents the first described example of a diverse Miocene fossil sea star fauna in Western Europe. The co-occurrence of these four families, which based on modern analogs have distinct ecologies (oreasterids and echinasterids are epibenthic, astropectinids are endobenthic, solasterids inhabit various depths), suggests they were transported by a natural event before rapid burial. The fossils are exceptionally well-preserved, with ossicles almost always in anatomical position, indicating a sudden mortality event possibly caused by episodic storms. Lacosteaster is the second fossil member of Solasteridae ever described, following Plesiosolaster moretonis from the Middle Jurassic of the United Kingdom.
Did You Know?
- Lacosteaster has twelve arms radiating from a proportionately small disc.
- The holotype specimen is housed in the Lauer Foundation in Illinois, United States.
- The fossil assemblage is dated to about 16 million years ago, during the late Burdigalian age of the early Miocene.
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