Read the story here. Advertise at Before It's News here.
Profile image
Story Views
Last hour:
Last 24 hours:

Shark skull evolution updated

% of readers think this story is Fact. Add your two cents.

Short one today,
updating an older graphic with the latest ReptileEvolution images in order (Fig. 1).

Figure 1. Shark skull evoluition updated today, June 2, 2021.

More taxa =
more parsimony, smoother transitions, greater detail, more support.

Loganellia is Early Silurian, so more primitive taxa are earlier, in the Ordovician.

start with Chondrosteus.

Multiple opercula (gill openings)
begin with Rhincodon.

Marginal teeth
start with Ginglymostoma.

Nasals extend beyond the jaws
(convergent with or reversal to sturgeons) with Ginglymostoma and Sphyrna, the hammerhead.

Nasals extend waaay beyond the jaws
in guitarfish (Rhinobatos) + sawfish (Pristis) on one branch and Squaloraja + the goblin shark (Mitsukurina) on another by convergence.

Nasals are much smaller
in Isistius and Ozarcus leading to Hybodus and bony fish, which also return to a single gill opening (as in Prohalecites Fig. 2, Amia, Fig. 1).

Ancestors of Gregorius also evolve to
the moray eel (Gymnothorax, not shown), Harpagofutator (Figs. 1, 2), Edestes, and Helicoprion (Fig. 1).

Ancestors of Gregorius also evolve to
spiny sharks, like Homalacanthus (Early Devonian, Fig. 2) so all more primitive taxa appeared earlier, in the Silurian.

Ratfish and Iniopterygians
arise from horn sharks like Heterodontus. These taxa also reduce the number of gill openings.

Torpedo rays
arise from hammerheads. Other skates, rays and manta rays have separate origins.

Paddlefish (Polyodon)
with a single gill opening arise from basking sharks (Cetorhinus) with multiple gill openings.

Figure 2. Representatives from the Early Devonian radiation that gave us bony fish, including Prohalecites and Homalcanthus.

This appears to be a novel hypothesis
of interrelationships (Fig. 3). If someone proposed this earlier, let me know so I can promote that citation.

Figure 3. Subset of the LRT focusing on elasmobranchs.

Don’t put all your ‘faith’ in one to a dozen traits
(like gill opeinings) in order to exclude taxa. That’s called “Pulling a Larry Martin.” Expand your taxon list and see where evolution takes your cladogram.

According to the LRT,
humans, bats, frogs, dinosaurs and pterosaurs all have shark ancestors, so we are all sharks. Something else to get used to.


Before It’s News® is a community of individuals who report on what’s going on around them, from all around the world.

Anyone can join.
Anyone can contribute.
Anyone can become informed about their world.

"United We Stand" Click Here To Create Your Personal Citizen Journalist Account Today, Be Sure To Invite Your Friends.

Please Help Support BeforeitsNews by trying our Natural Health Products below!

Order by Phone at 888-809-8385 or online at M - F 9am to 5pm EST

Order by Phone at 866-388-7003 or online at M - F 9am to 5pm EST

Order by Phone at 866-388-7003 or online at M - F 9am to 5pm EST

Humic & Fulvic Trace Minerals Complex - Nature's most important supplement! Vivid Dreams again!

HNEX HydroNano EXtracellular Water - Improve immune system health and reduce inflammation

Ultimate Clinical Potency Curcumin - Natural pain relief, reduce inflammation and so much more.

MitoCopper - Bioavailable Copper destroys pathogens and gives you more energy. (See Blood Video)
Oxy Powder - Natural Colon Cleanser!  Cleans out toxic buildup with oxygen! 
Nascent Iodine - Promotes detoxification, mental focus and thyroid health.
Smart Meter Cover -  Reduces Smart Meter radiation by 96%!  (See Video)

Report abuse


    Your Comments
    Question   Razz  Sad   Evil  Exclaim  Smile  Redface  Biggrin  Surprised  Eek   Confused   Cool  LOL   Mad   Twisted  Rolleyes   Wink  Idea  Arrow  Neutral  Cry   Mr. Green

    Load more ...




    Email this story
    Email this story

    If you really want to ban this commenter, please write down the reason:

    If you really want to disable all recommended stories, click on OK button. After that, you will be redirect to your options page.