Meet Birkenia, a small and streamlined jawless fish from the Silurian period. Birkenia is significant in palaeontology for its well-preserved fossils that provide insights into the evolution of early vertebrates.
Taxonomy and Classification
Kingdom: Animalia
Phylum: Chordata
Class: Anaspida
Order: Birkeniiformes
Family: Birkeniidae
Geological Time & Habitat
Geological Time Period: Silurian (approximately 430 million years ago).
Typical Environment: Birkenia thrived in shallow marine environments, where it likely fed on small particles and microorganisms.
Discovery & Classification
Date: Late 19th century
Discovery Location: Scotland
Discovering Paleontologist(s): Ramsay H. Traquair
The genus was named by Ramsay H. Traquair in the late 19th century. It has been well-studied due to the abundance of well-preserved specimens.
Physical Characteristics
Size and Weight: Birkenia was a small fish, typically around 10 centimetres in length.
Unique Features: It had a streamlined body with a hypocercal tail, which helped it to maneuver in the water. Unlike many other early vertebrates, Birkenia lacked bony armour. Its body plan can be loosely compared to modern small, streamlined fish-like anchovies in terms of shape and size.
Synapomorphies
Birkenia had a hypocercal tail, where the vertebrae extend into the lower lobe, which is more developed than the upper lobe. It also had unique body fins along the entire sides of its body, which are not homologous with the fins seen on modern fish.
All members of the class Anaspida are vertebrates but true agnathians on the Cyclostome line of the vertebrate tree, meaning they are more closely related to hagfishes, lampreys, and conodonts than to today’s fish or any jawed vertebrates like us and T Rex.
Known Species
Birkenia elegans
Birkenia gracilis
Behaviour & Ecology
Diet: Likely a filter feeder, consuming small particles and microorganisms from the water.
Behaviour: Birkenia was probably an active swimmer, using its streamlined body to navigate through its shallow marine habitat.
Ecological Interactions: Coexisted with other early vertebrates and various invertebrates of the Silurian seas.
Fossil Discoveries
Significant Discoveries Timeline: Late 19th century: First discovered by Ramsay H. Traquair.
Key Paleontologists: Ramsay H. Traquair, Erik Stensiö
Fossil Sites: Scotland; Ludlow Bone Bed, England. These sites provide significant insights into the Silurian ecosystems.
Current Specimen Locations
Natural History Museum, London
National Museum of Scotland.
The specimens at these museums are among the best-preserved and most studied.
Scientific Research & Theories
Recent Studies: Focus on the phylogenetic position of Birkenia within early vertebrates and its anatomical adaptations.
Scientific Debates: Ongoing debates about the precise evolutionary relationships of Birkenia and other anaspids. Some studies suggest closer affinities with other jawless fish like lampreys.
Extinction Theories
Theories and Debates: Birkenia and other anaspids declined towards the end of the Silurian period. This is likely due to changing environmental conditions and competition with other emerging vertebrate groups.
Cultural & Historical Impact
Pop Culture and Media: Birkenia has not been widely featured in popular media but is occasionally mentioned in documentaries about early vertebrate evolution.
Pop Culture Influence: Due to its obscurity, Birkenia has not significantly influenced popular culture.
Interesting Facts & Trivia
Hypocercal Tail: Birkenia’s tail structure is unique among early vertebrates, indicating a specialized mode of swimming.
Streamlined Body: Its lack of bony armour suggests a lifestyle that prioritises agility and speed over protection.
Discover More Fascinating Anaspids
Birkenia has some famous cousins like Lasanius, Pharyngolepis, Pterygolepis and Rhyncholepis (previously known as Anaspis, the genera that gave Anaspids their name but has since fallen away).
Other extremely interesting Anaspida are the Canadian discovery with the insanely large hypocercal tail, Endeiolepis and Scotland’s spiny-backed Cowielepis.
Documentaries Featuring Some Awesome Early Vertebrates Like Birkenia
They’re not always 100% accurate because we make new scientific discoveries all the time. But documentaries at least deliver the gist of the information in a fun and engaging way. Just click play, hit full screen and enjoy hours’ worth of awesome documentaries on first animals, right here…
1. Ancient Oceans
2019
Not just about vertebrates, but featuring some of the most awesome ancient fishes. This short documentary about early oceans and extinction events has two episodes and is available through Curiosity Stream here.
2. Australia: A Time Traveller’s Guide Episode 2
Richard Smith, 2012
Though not specifically focused on vertebrates, Episode 2 of the charming Australia: A Time Traveller’s Guide (Australia’s First 4 Billion Years) is all about tracking the continent’s record of animals’ invasion of land. Starting off with features of early vertebrate fish Arandaspis to later placoderms and reefs of the Devonian, as well as invertebrate tracks on land in the Silurian.
You can also find it on AppleTV here.
3. Animal Armageddon Episode 2
Animal Planet, 2019
It’s hard to track down a good copy of this one, but Animal Armageddon features quite a few vertebrate evolutionary stories, pegged on the major mass extinctions they faced. This one specifically is during the Devonian, the age of fishes (vertebrates).
Also available on Amazon here.
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Enjoy the journey of discovery through Earth’s ancient past, geology, big ideas and, of course, awesome prehistoric life.
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