Life Through Geologic Time

Living Fossils - Queensland Lungfish

The Queensland Lungfish is the only surviving member of its Family, Ceratodonitidae, and the Order Ceratodontiformes. That doesn’t mean that there aren’t other lungfish, though! There are six extant species, including the Queensland Lungfish. 

The Queensland Lungfish is a lobe-finned fish, sometimes called fleshy-finned fish, which is interesting enough because Tetrapoda descended from Sarcopterygii (Lobe-finned fish.) (Remember, evolution isn’t progress, it’s diversification through change through decent.) (See Tiktaalik song) It is one of the six extant species of Dipnoi (lungfishes) which flourished during the Devonian, and is the most primitive surviving member of Dipnoi. It can survive out of water for several days, but, unlike its four African cousins, it cannot survive total water depletion and must be kept moist. Fossils almost identical to the Queensland Lungfish have been found, indicating that it has remained nigh unchanged since 100 mya , and, therefor, is a viable living fossil.

Alright, friends, let’s talk about evolution. FIRSTLY, I MUST SAY THIS, AND I MUST SAY IT IN BOLD AND CAPS LOCK, THE ABOVE PICTURE IS NOT EVOLUTION, IT IS AN ACCIDENT THAT LIKELY AROSE FROM THIS IMAGE:  Now that that’s said, let’s talk about evolution, and its process, natural selection.

Evolution:

Evolution is change with descent. Now what does that mean, “change with descent”? Well, change with descent is just how organisms change genetically with descent, that is, how organisms’ offspring change from the organisms which they arose from. IT IS NOT “PROGRESS,” AND IT IS FOOLISH TO THINK IT IS, EVOLUTION IS THE ADAPTATION TO A LOCAL AND CHANGING ENVIRONMENT, OR, MERELY, GENETIC CHANGE WITH DESCENT (as stated (repeatedly) above.)

Natural Selection:

Contrary to what many believe, Natural Selection is not the same as Evolution. Natural selection follows three relatively undeniable principles, which are as follows:

Variation: Life varies. Whop-dee-doo. I am different from every other Homo sapiens sapiens and there’s nothing you can do about it. Coincidentally, I am also different from every armadillo, but we’ll talk about that later if you’re good.

Heredity: When a mommy and a daddy get “it” on, and their genes cross and get together, they make a new sequence that probably never existed before then. This is, of course, true only for organisms that sexually reproduce. Occasionally asexual organisms will make babies with themselves, but this doesn’t usually yield any genetic change. When it does, however, whoop-dee-doo, we have a new organism that has a new DNA sequence

Superfecundity: I particularly like this principal because it’s fun to say and is, some might say, a bit morbid. Superfercundity is the principle that more offspring are produced than could ever possibly survive to adult hood and mate to make more little organisms. 

The Inference: The inference is that, on average, the organisms better suited for their local and changing environment will survive to pass on their traits, but not necessarily, as something may happen to an organism, it could fall off a cliff, be run over by a car, be attacked by a starving horde of flesh eating slugs, et cetera. If said organism does pass on its genetics, the offspring will, on average, look similar to the parents, yet different.

Dammit… I had it finished too… Third times the charm… T_T

Basilosaurus, from the Greek basileus and sauros meaning king and lizard respectively, has a somewhat ironic name in that it is actually a mammal, more specifically an early whale. It lived in the late Eocene, 40 - 34 mya. A Sir Richard Owen wanted to rename it Zeuglodon (Yoked Tooth), but, because of the rules of taxonomy, it remained Basilosaurus, much like how Brontosaurus is actually Apatosaurus. 

The average size of Basilosaurus was about 18 meters (60 feet) in length. It is believed to be the largest animal of its time. It’s vestigial hind limbs are of great interest to paleontologists and evolutionary biologists alike. They were basically useless, being only .6 meters (2 feet) in length. Analysis shows that they could only flap them between two positions. Basilosaurus had extremely long vertebrae and was the closest whales ever came to being snake-like (I shit you not, that is what Wikipedia says. It’s not a direct quote, mind you). It likely moved in an anguilliform (eel-like) fashion (mostly horizontal movement) and had a small fluke to assist with vertical movement. It is believed that it was incapable of terrestrial locomotion. It had a smaller head (you could not fit a melon in it like you could with modern toothed whales) and brain than modern toothed whales, and it is suspected that they did not have the social capabilities of modern whales.

On a cultural note, it is the state fossil of both Mississippi and Alabama. Also, its fossils were so prevalent and large in Southern America, that its fossils were used as furniture, much like how Shonisaurus’s (an icthyosaur) vertebrae were used as plates by miners in the Shoshone Mountains when it was first discovered. Herman Melville mentions the discovery of Basilosaurus in chapters 104-105 in Moby-Dick.