Which is the most primitive freshwater fish species?

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Ichthyotopia

Candiru
MFK Member
Jun 26, 2009
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NJ
Im thinking lunfish or polypterus, but wat does everyone else think? does anyone have a phylogeny diagram to show which is the most ancient species in order?
 
I don't have any diagrams to show this, but I'll list a few of the most primitive freshwater fishes.

  1. Lampreys (Family Petromyzontidae)-- Some live strictly in freshwater.
  2. Sharks, rays, sawfishes, etc. (Class Chondricthyes)-- Some live strictly in freshwater.
  3. Lungfish (Subclass Dipnoi)-- The Australian lungfish is the most primitive of this subclass.
  4. Sturgeons and Paddlefishes (Order Ancipenseriformes)
  5. Reedfishes and Bichirs (Order Polypteriformes)
  6. Gars (Family Lepisosteidae)
  7. Bowfin (Amia calva)
After these fishes, all that is left are the Teleosts which comprise the remaining fishes.

I'm certain that #1-3 are in the correct order, but it gets kind of tricky for the remaining four groups of fishes although I'm pretty sure that they're in the correct order.
 
Wiggles92 said:
I don't have any diagrams to show this, but I'll list a few of the most primitive freshwater fishes.

  1. Lampreys (Family Petromyzontidae)-- Some live strictly in freshwater.
  2. Sharks, rays, sawfishes, etc. (Class Chondricthyes)-- Some live strictly in freshwater.
  3. Lungfish (Subclass Dipnoi)-- The Australian lungfish is the most primitive of this subclass.
  4. Sturgeons and Paddlefishes (Order Ancipenseriformes)
  5. Reedfishes and Bichirs (Order Polypteriformes)
  6. Gars (Family Lepisosteidae)
  7. Bowfin (Amia calva)
After these fishes, all that is left are the Teleosts which comprise the remaining fishes.

I'm certain that #1-3 are in the correct order, but it gets kind of tricky for the remaining four groups of fishes although I'm pretty sure that they're in the correct order.
Click to expand...

I think gars and bowfins are much older than reedfish and bichirs. Even arowanas are much older than bichir. If I can remember on the diagram gars, bowfins and arowanas appeared around Jurassic period and bichirs and reedfish appeared around late cretaceous. I could be wrong. Too lazy to search in google. Using my iphone.
 
King-eL said:
I think gars and bowfins are much older than reedfish and bichirs. Even arowanas are much older than bichir. If I can remember on the diagram gars, bowfins and arowanas appeared around Jurassic period and bichirs and reedfish appeared around late cretaceous. I could be wrong. Too lazy to search in google. Using my iphone.
Click to expand...
Yeah, I remember Aros and Gars are older than Bichirs.
 
Arowanas definitely are not older than bichirs since they're known from as far back as the Late Cretaceous while bichirs are known from as far back as the late Devonian (although there is a gap in the fossil record from that time period until the Early Cretaceous) plus molecular data puts them as the most primitive of their class (Actinopterygii). Honestly, any Teleost, including arowanas, knife fishes, and the other 96% of fishes, don't really even come close to the level of "primitiveness" that is displayed by bichirs and other primitive fishes.

If anything, the sturgeons and paddlefishes should be bumped down on the list to #5, and the reedfishes and bichirs should be moved to #4 since sturgeons and paddlefishes are only known from the Late Cretaceous. Gars are known from the Late Cretaceous onward and bowfins are known from the Triassic onward, but gars are still considered to be the more primitive of those two because of their morphology rather than the fossil record, especially when one considers how incomplete the fossil record is.

I know that this all is still pretty confusing, but this is what I'm getting from my textbook on the biology of fishes (Bond's Biology of Fishes, 3rd Ed.)
 
Actually, aros came around in the late cretaceous, while gars appeared in the early cretaceous. Meanwhile, Polypterus fossil records have been found that date back to the Triassic, so they are older than both aros and gars.

Sturgeon also appear about 200 million years ago, so they're about as old as polys. The earliest lungs appeared in the Devonian, so they're older than all other fish except for Chondricthyes (which are over 420 million years old). Not sure where lampreys fall, they're not technically fish though. Also, bowfin are a little tricky because they have ancestors as early as the Jurassic, not sure where the current sp. falls though.

So, the list that Wiggles92 posted is 100% correct. Here's a little bit of extra info added to it, hope he doesn't mind:

1. Sharks, rays, sawfishes, etc- Silurian (About 444 to 416 million years ago)
2. Lungfish- Devonian (416 to 359.2 million years ago)
3. Sturgeons and Paddlefishes- At least 200 million years ago, not sure of period.
4. Reedfishes and Bichirs- Triassic (250 to 200 million years ago)
5. Gars- Early Cretaceous (About 146 to 100 million years ago)
6. Arowanas/Arapaimas- Cretaceous (About 146 to 65 million years ago)
7. Bowfin- Not sure of period.

Hope that helps!
 
I was typing while you posted, hahaha. Oh well, I guess a little extra info never hurt anyone.
 
Neither of those diagrams show linear time, so you can't tell from them which fish came first. The first diagram is a phylogenetic diagram, which means that it shows how closely groups of organisms are related on a molecular and evolutionary level. The second one is also phylogenetic, just set up differently.
 
well i meant it supports in terms of evolution as to which is more primitive, but yes it doesn't show the age of the species.
 
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