Jack Stack
@jackstack.bsky.social
Trophy husband, PhD vertebrate paleontologist. 0 time rank 1 wow PVP player. I also write about the history of fishes: https://fishhistory.substack.com/. He/him
Yeah, no. I spent ten years studying and working for this title. Ten years of low pay and hard work to become an expert in my field. As my namesake and grandfather (the first Dr. Jack Stack) would say, my first name is doctor.
November 24, 2025 at 5:56 PM
Yeah, no. I spent ten years studying and working for this title. Ten years of low pay and hard work to become an expert in my field. As my namesake and grandfather (the first Dr. Jack Stack) would say, my first name is doctor.
Reading about Pennsylvanian fishes, absolute horror show from my master's advisor dissertation (Michael Gottfried, 1993).
November 21, 2025 at 3:11 PM
Reading about Pennsylvanian fishes, absolute horror show from my master's advisor dissertation (Michael Gottfried, 1993).
Reading about Permian ray-finned fishes and I would like to speak with the manager. Who gave Dorypterus the permission to be like this? From Westoll (1931).
November 18, 2025 at 4:12 PM
Reading about Permian ray-finned fishes and I would like to speak with the manager. Who gave Dorypterus the permission to be like this? From Westoll (1931).
21) Finally, the result that will get fruit thrown at me. The phylogenetic classification of living ray-finned fishes and a hundred years of precedent says that bichirs and reedfish are the earliest diverging lineage of living ray-finned fishes. Might I gently suggest an alternative?
November 18, 2025 at 4:22 AM
21) Finally, the result that will get fruit thrown at me. The phylogenetic classification of living ray-finned fishes and a hundred years of precedent says that bichirs and reedfish are the earliest diverging lineage of living ray-finned fishes. Might I gently suggest an alternative?
18) I also took a look at Brachydegma, which thankfully was re-described in great detail by Argyiou, Giles, and Friedman while I was in the planning stages of the project. Although I arrived at a slightly different placement, I can't emphasize enough how much that work improved my own.
November 18, 2025 at 4:22 AM
18) I also took a look at Brachydegma, which thankfully was re-described in great detail by Argyiou, Giles, and Friedman while I was in the planning stages of the project. Although I arrived at a slightly different placement, I can't emphasize enough how much that work improved my own.
15) But wait, there's more! I included some other problematic taxa that look out of place. Like Coccolepis here. Coccolepis, and coccolepids, are Jurassic-Cretaceous fishes that look startlingly like Paleozoic actinopterygians. But, there is a debate as to their relationships.
November 18, 2025 at 4:22 AM
15) But wait, there's more! I included some other problematic taxa that look out of place. Like Coccolepis here. Coccolepis, and coccolepids, are Jurassic-Cretaceous fishes that look startlingly like Paleozoic actinopterygians. But, there is a debate as to their relationships.
13) This is 'Platysomus' schultzei, another very odd 'Bob'. I found that the original author, Jiri Zidek, was 100% correct in his anatomical interpretation. My phylogenetic analysis proved him correct in this being a Bobasatraniid, a member of an extinct, neopterygian-like clade.
November 18, 2025 at 4:22 AM
13) This is 'Platysomus' schultzei, another very odd 'Bob'. I found that the original author, Jiri Zidek, was 100% correct in his anatomical interpretation. My phylogenetic analysis proved him correct in this being a Bobasatraniid, a member of an extinct, neopterygian-like clade.
12) This tiny, coin-shaped fish has evolved a more independently mobile upper-jaw (meaning it is less attached to the cheek) ~320 million years ago! Also, this taxon has a tail fin that is considerably more symmetrical than other Paleozoic fishes. The rest of the anatomy suggests convergence.
November 18, 2025 at 4:22 AM
12) This tiny, coin-shaped fish has evolved a more independently mobile upper-jaw (meaning it is less attached to the cheek) ~320 million years ago! Also, this taxon has a tail fin that is considerably more symmetrical than other Paleozoic fishes. The rest of the anatomy suggests convergence.
10) With my characters in hand, and a rogue taxon (boo!) identified, we can talk about the phylogenetic results. This paper started as an attempt to figure out where some truly weird fossil fishes fit, and did not disappoint.
November 18, 2025 at 4:22 AM
10) With my characters in hand, and a rogue taxon (boo!) identified, we can talk about the phylogenetic results. This paper started as an attempt to figure out where some truly weird fossil fishes fit, and did not disappoint.
8) I used the Teleost Anatomy Ontology to analyze my characters, giving us a pseudo phylogenetic tree. This shows that most of our characters are from the head, and that scale and fin characters separate out. Essentially, we need to think of our character set of having at least three partitions.
November 18, 2025 at 4:22 AM
8) I used the Teleost Anatomy Ontology to analyze my characters, giving us a pseudo phylogenetic tree. This shows that most of our characters are from the head, and that scale and fin characters separate out. Essentially, we need to think of our character set of having at least three partitions.
7) Ontologies helped me create rigorous characters and create a computable framework of morphology. That is, build a Bayesian model for phylogenetics that is anatomically informed. The basic concept is that the ontology, built by Wasila Dahdul, defines the entities and their interrelationships.
November 18, 2025 at 4:22 AM
7) Ontologies helped me create rigorous characters and create a computable framework of morphology. That is, build a Bayesian model for phylogenetics that is anatomically informed. The basic concept is that the ontology, built by Wasila Dahdul, defines the entities and their interrelationships.
6) The process of character creation is spelled out here, where we distinguish between neomorphic (presence vs. absence) and transformational (change in form) characters. Using rigorous character construction methods from people like Paul Sereno and Martin Brazeau, I was able to make the bridge.
November 18, 2025 at 4:22 AM
6) The process of character creation is spelled out here, where we distinguish between neomorphic (presence vs. absence) and transformational (change in form) characters. Using rigorous character construction methods from people like Paul Sereno and Martin Brazeau, I was able to make the bridge.
My mentees and I are cooking up some fun papers, can’t wait to share what’s next for weird fish paleontology.
November 18, 2025 at 3:36 AM
My mentees and I are cooking up some fun papers, can’t wait to share what’s next for weird fish paleontology.
Me watching The Meg as a fish scientist.
November 10, 2025 at 10:35 PM
Me watching The Meg as a fish scientist.
Crocodylians surviving the K-Pg extinction.
November 6, 2025 at 3:24 PM
Crocodylians surviving the K-Pg extinction.
There’s going to be more theropod drama isn’t there.
November 5, 2025 at 5:11 PM
There’s going to be more theropod drama isn’t there.
Early actinopt anatomy in a nutshell
November 3, 2025 at 4:46 PM
Early actinopt anatomy in a nutshell
Settling down to watch football all weekend
November 1, 2025 at 4:31 PM
Settling down to watch football all weekend
Students are dissecting invertebrates today, was really impressed with this grasshopper dissection.
October 30, 2025 at 10:35 PM
Students are dissecting invertebrates today, was really impressed with this grasshopper dissection.
First draft of the response letter going great.
October 28, 2025 at 7:22 PM
First draft of the response letter going great.
The early ray-finned fish worker experience.
October 28, 2025 at 2:39 PM
The early ray-finned fish worker experience.
What kind of bee is this?
October 26, 2025 at 4:33 PM
What kind of bee is this?
Me pretending to know teleost taxonomy
October 17, 2025 at 11:13 PM
Me pretending to know teleost taxonomy