|Astronomy and Geology|
|Auster • History of Auster|
|Benthochordata • Thalassaflora|
- See also: Terra Chordata § Thalassaflora
|Clavelina moluccensis, ancestor of the Thalassaflora|
|about 200,000 species|
The Thalassaflora are one of the most diverse, common, and ancient groups on the terraformed planet of Auster, in the Epsilon Eridani system, surviving any extinction event, climatic change, or tectonic shift the planet could throw at them. They have in their origins in ascidiaceans like the blue sea squirt, transported to the planet some 400 million years ago. Since then, this one population has evolved into many groups now commonplace on the planet, the Thalassaflora being one of these. They get their name, which means "open sea flowers" from the vague resemblance of many species to free floating (or sessile, in some derived taxa) flowers. -flora is a common suffix for its subgroups.
The Thalassaflora have many notable point about their anatomy, because of one major difference from their ancestors - free floating. No longer sessile, they needed a way to move, which the bell sea squirts they descended from never had to deal with. The first step to this was to loosen up the previously rigid skin, instead going back to a soft, flexible structure with more focus at muscles at the base, which has become the front of the animal. All living taxa retain this feature, though more primitive forms are very common in the fossil record, showing great diversity, disappearing completely after a mass extinction, timed with the split of the second supercontinent.
The next revolution, and one of the real characteristic features of nearly all extant taxa, was the notable change in mouth design and digestive system that led to the use of a single "mouth" to inhale and exhale food. These changes in digestive track are very complex. However, the other opening, which is the "out door" in earthly taxa, has become much more prominent on the animal, and is not at all connected to the digestive system. Instead, it is used in an undulating manor, pushing the animal forward. Only two groups extant lack this feature, one using inflation and deflation of a special chamber to give limited movement control, the other floating on the surface and using a semi-rigid, sail-like appendage to get around. This design led to multiple different paths in their evolution, different groups using different modified designs in order to move.
The Thalassaflores are among the most common groups in Austerian rocks, as well as some of the oldest life of Auster.
In order to understand their ancestry, you need a definition of what the group is defined by, and details of the original Thalassaflore. This form is defined by one thing: free floating. Not all it's descendents were like this this, but the first form was. However, for the first ~30 million years, they were firmly attached.
At first, for several of the first dozen million years, they were relatively unchanged. The first, and only, notable related group was the paraphyletic Caudaflora. This extinct group was already showing some of the body changes of the Thalssaflores, and these were planted on long, string like structures erupting from the bottom of the creature, which is in modern forms firmly attached to the rock the creature inhabits. This evolved from the increasing height of the creature, which eventually became unconventional. This led to longer strings, and a more condenced organ system, because the tall stem-caudaflores had enlongated digestive tracks. Their name translates to "tailed flowers", because of the long stems that hold them down. They eventually left the seafloor behind, and floated into the open sea.
Major extinction Events
Dorsaflora: "Back Flowers"
The sails, although may appear simple, are actually quite complex. This starts with the tunic layer, which has as opposed to being thined out and loosened like before, has been replaced by a fundamentally different tissue. This is rather convergent with a large subgroup of Monostomaflores. Thought as opposed to the very flexible model these forms would come to evolve, these have a stiff structure, and the sail is practically immobile. This caused the sail to evolve a shape the doesn't require movement of the structure.
The general anatomy of the dorsaflores has stayed relatively unchanged for millions of years. In the past they were greatly successful, sailing seas across the planet, but are today restricted to the Chronos Sea, which is surrounded on three sides by the Northern Continent of Borealia. Althought in the past they had a variety of groups, they are restricted to two groups in the present.
The first, and more common, are the Smiloformids. A recent group, having evolved in the last ~30 million years. Despite general replacement of the Dorsaflores, the Smiloformids are still by far the dominant predators of surface plantonic food. With 27 species in 7 genera, they are also quite diverse. They get their name from Smiloformis, which is characterised by its short, butcher's knife shaped sail. In fact, the entire family generally sports these sorts of sails.
The second are the tall sailed Erectonotids. A more ancient groups, they've been around since begore the Nyx traps events. Mildly successful at the time, they were hit hard. Only one genus restricted to a couple large bays survived. They've been relatively uncahnged since, thought still only exist in coastal waters. Having 13 species in 3 genera, they are less diverse then their cousins. They feed almost entirely on Caerulaephytans, along with some bacteria and cyanobacteria. And even then, only a single genus deviates to the latter two. They have much taller sails, catching coastal winds to travel at surprisingly somewhat fast speeds.