Streptognathodus

Streptognathodus was a group of tiny, ancient sea creatures that lived a very long time ago, from the Late Carboniferous to the Early Permian periods. These small organisms belonged to a group called conodonts. They were important parts of the ocean’s ecosystem, even though they were mostly made of soft tissue and very small.

Scientists study fossils of Streptognathodus to learn about Earth’s history during these ancient times. Their fossilized teeth and other tiny remains help experts understand how life evolved and how the climate and oceans changed over millions of years.

Because Streptognathodus lived during a time when the continents were shifting, they give clues about how the world looked and worked back then. These fossils are especially useful for dating rocks and understanding the order of events in Earth’s deep past.

Use in stratigraphy

The top of the Kasimovian stage is near when the species Streptognathodus zethus first appeared. The Kasimovian stage is divided into three areas based on tiny, ancient creatures called conodonts:

• Idiognathodus toretzianus Zone
• Idiognathodus sagittatus Zone
• Streptognathodus excelsus and Streptognathodus makhlinae Zone

The start of the Gzhelian stage is marked by the first appearance of Streptognathodus zethus. The end of this stage, which also marks the end of the Silesian and the start of the Permian period, is when Streptognathodus isolatus first appears.

The Gzhelian stage has five areas based on the Streptognathodus genus:

• Streptognathodus wabaunsensis and Streptognathodus bellus Zone
• Streptognathodus simplex Zone
• Streptognathodus virgilicus Zone
• Streptognathodus vitali Zone
• Streptognathodus simulator Zone

The start of the Asselian stage, which is also the start of the Cisuralian series and the Permian period, is when fossils of Streptognathodus isolatus first appear. The global reference point for this is near Aqtöbe in Kazakhstan. The end of the Asselian stage is when Streptognathodus postfusus first appears.

The Asselian stage includes five areas:

• zone of Streptognathodus barskovi
• zone of Streptognathodus postfusus
• zone of Streptognathodus fusus
• zone of Streptognathodus constrictus
• zone of Streptognathodus isolatus

The start of the Sakmarian stage is when Streptognathodus postfusus first appears. The end of the Sakmarian stage is when fossils of Sweetognathus whitei and Mesogondolella bisselli first appear.