Hemiaster nasulatus Fossil Echinoid Cretaceous Turonian Chalk Dorset England Certified | Rare Sea Urchin from Ringstead Bay Plana Zone

Description

Authentic Hemiaster nasulatus Fossil Echinoid from Dorset

This listing features a genuine Hemiaster nasulatus fossil echinoid collected from the Cretaceous Middle Chalk, Turonian stage, Plana Zone at Ringstead Bay, Dorset, England. Ringstead Bay is a well-known fossil locality along the Jurassic Coast, and its chalk deposits are particularly rich in well-preserved echinoids. The specimen shown in the photographs is the actual fossil you will receive, with a 1 cm scale cube included for accurate sizing.

All of our fossils are 100% genuine specimens, supplied with a Certificate of Authenticity to confirm provenance, making them perfect for collectors, students, or natural history enthusiasts.

Geological Setting – Middle Chalk, Turonian, Plana Zone

This specimen dates to the Turonian stage of the Late Cretaceous (approx. 93.9–89.8 million years ago). The chalk at Ringstead Bay is part of the Middle Chalk sequence, deposited in warm shallow seas that covered much of southern England during this time.

The Plana Zone, named after the index ammonite Collignoniceras plana, provides a highly precise stratigraphic framework. The occurrence of Hemiaster nasulatus within this zone makes it an important biostratigraphic indicator, helping palaeontologists refine correlations within the Cretaceous chalk successions of Europe.

Fossil Type and Classification

• Species: Hemiaster nasulatus
• Genus: Hemiaster
• Order: Spatangoida
• Superfamily: Spatangoidea
• Family: Hemiasteridae

Hemiaster echinoids are irregular sea urchins, commonly referred to as “heart urchins,” that evolved specialised adaptations for life buried within soft marine sediments. Hemiaster nasulatus is particularly associated with Turonian chalk deposits and is a distinctive fossil within the British record.

Morphological Features

This specimen preserves the classic features of Hemiaster nasulatus:

• A heart-shaped test (shell) with a bilaterally symmetrical outline.
• A deep anterior sulcus (groove) running towards the peristome (mouth), aiding in sediment feeding.
• Petaloid ambulacra forming a clear star-like pattern across the dorsal surface.
• A ventral peristome and a posterior periproct, reflecting its adaptation to a burrowing lifestyle.
• The overall form is more robust than some related echinoids, making it an easily recognisable species.

These adaptations allowed the species to live as an infaunal deposit feeder, burrowing just beneath the chalk seafloor and feeding on organic particles within sediment.

Scientific and Collector Importance

Hemiaster nasulatus is highly valued both scientifically and among fossil collectors. In geology, it is used as an important biozonal fossil, marking specific intervals within the Turonian stage. Its presence in the Plana Zone helps refine the stratigraphy of chalk deposits, making it significant for Cretaceous research.

For collectors, this fossil offers a rare and distinctive specimen from the classic locality of Ringstead Bay. Its preservation, scientific importance, and association with a well-defined stratigraphic zone enhance its desirability as both a display piece and a study fossil.

Depositional Environment

The chalk seas of the Turonian were warm, stable, and nutrient-rich, dominated by the remains of coccolithophores and other planktonic organisms. These conditions provided excellent preservation potential, enabling delicate echinoid tests such as Hemiaster nasulatus to fossilise in remarkable detail. The fine chalk matrix preserved not only the shape of the echinoid but also its distinctive surface features, offering insights into its ecology and mode of life.

Guarantee of Authenticity

Every fossil we sell is 100% genuine, carefully selected for its quality and scientific accuracy. Each specimen comes with a Certificate of Authenticity, confirming its provenance. The fossil pictured is the exact specimen you will receive, with size references shown.

This Hemiaster nasulatus fossil echinoid from the Turonian Middle Chalk of Ringstead Bay, Dorset represents an exceptional opportunity to own a scientifically significant and beautifully preserved piece of England’s Cretaceous past.