However a wide gamut phylogenetic analysis based on traits can recover the last known taxon with jaws lacking teeth (e.g. Chondrosteus), and it can recover the first known taxon with jaws lined with teeth (e.g. Stegostoma, Figs 1,2). We looked at the origin of marginal teeth erupting from pre-premaxillary tissues and pre-maxilla tissues arising from the large supporting lacrimal cartilage earlier here.
Just because you have access to a fossil sawfish does not mean you have to write a paper about it. It is inappropriate to glorify the wrong taxon while disregarding phylogeny. You might get published in Nature, but a week later you may realize you were talking about an irrelevant taxon. Thus all your work and all your conclusions were irrelevant to the subject at hand. It was a waste of time. Taxon exclusion is the number one problem in paleontology. Start with a valid cladogram before you even consider writing a paper about anything.
If you want to study the origin of marginal teeth, study the transitional taxa that represent the last absence of, then the first appearance of marginal teeth: Chondrosteus and Stegostoma. This hypothesis has been online since October 2021.
References Cook TD, Prothero J, Brudy M and Magraw JA 2022. Complex enameloid microstructure of †Ischyrhiza mira rostral denticles. Journal of Anatomy online here.
Barbels are short to extended cone-shaped, flexible, sensory structures surrounding the oral cavity of chordates, including some vertebrates and all cephalopods by homology, as we learned earlier here.
In basal vertebrates barbels (= buccal cirri) largely disappear. Then barbels reappear in catfish and cave fish as reported below, probably by reversal. In other words, genes in charge of producing barbels were turned off in most fish, but those genes were turned on again in catfish and cave fish.
Here’s the backstory:
Pre-chordates ancestral enoplid nematodes: six to 23 converging barbels (Fig 1).
Chordates lancelet: eight+ buccal cirri = tiny transparent barbels around the oral cavity (Fig 4). hagfish: six to eight barbels around the oral cavity: four above, two off the corners (Fig 1).
Vertebrates catfish: (genus Ictalurus): eight long, flexible barbels around the mouth: two above, two lateral and four under the chin (Fig 2). cavefish (genera Kryptoglanis and Phreatobius): eight barbels around the mouth: four above, four below (Fig 3). These taxa are basal to electric eels and knife fish in the LRT.
Cephalopods nautilus: up to 90+ arms = barbels (Fig 4). squids and octopuses: eight arms = barbels, plust two extendible tentacles in squids and cuttlefish.
This appears to be a novel hypothesis If not, please provide a citation so I can promote it here.
Daver et al 2022 confirm evidence for bipedalism 7mya in Sahelanthropus (Fig 1). From the abstract, “The morphology of the femur is most parsimonious with habitual bipedality, and the ulnae preserve evidence of substantial arboreal behaviour. Taken together, these findings suggest that hominins were already bipeds at around 7 Ma but also suggest that arboreal clambering was probably a significant part of their locomotor repertoire.”
Earlier the large reptile tree (LRT, 1235 taxa, subset Fig 2) nested Sahelanthropus (Fig 1) in the gibbon lineage leading to humans, separate and apart from Australopithecus in the ape lineage (Fig 2). Gibbons are the only other extant anthropoids that run bipedally. Thus Sahelanthropus, as a transitional taxon, would have also run bipedally based on phylogenetic bracketing.
From April 2022:
From the abstract “Bipedal locomotion is one of the key adaptations that define the hominin clade. Evidence of bipedalism is known from postcranial remains of late Miocene hominins as early as 6 million years ago (Ma) in eastern Africa. Bipedality of Sahelanthropus tchadensis was hitherto inferred about 7 Ma in central Africa (Chad) based on cranial evidence. Here we present postcranial evidence of the locomotor behaviour of S. tchadensis, with new insights into bipedalism at the early stage of hominin evolutionary history.”
The LRT also inferred bipedality based on phylogenetic bracketing. Australopitecines were bipedal by convergence.
Workers are still not including gibbons in hominid studies. Not sure why. Tradition, perhaps. The authors did wonder, “And did bipedalism evolve before, during or after the split between … among closely related species, a phenomenon known as convergence.”
It’s not often that a mammal jaw fragment is considered here (due to too few traits). So Asiapator (Fig 1) is a notable exception now used to highlight traditional interrelationships (see below) vs those recovered by the large reptile tree (LRT, 2135 taxa, subset Fig 2).
From Lopatin and Averinov 2022: “Asiapator onchin gen. et sp. nov. is based on a dentary fragment from the middle Eocene (Irdinmanhan) Khaychin Formation at Khaychin Ula 3 locality, Mongolia. This is the first record of the Apatemyidae in Central Asia. Asiapator has only one lower incisor as in all apatemyids except Unuchinia from the Paleocene of North America.”
An excluded taxon, Brachyerix, is more primitive than Apatemys in the LRT (Fig 2) and has smaller, more primitive incisors, like those in Asiapator (Fig 1).
From Averinov 2022: “Apatemiids were a small peculiar group of small placental mammals of the Paleogene of the Northern Hemisphere. They lived on trees and fed on xylophagous insects, which were extracted from the bark and wood with the help of strongly elongated fingers of the forelimbs and powerful enlarged incisors.
Apatemiids (Fig 1) are similar to, but convergent with aye-ayes (= Daubentonia, Fig 1), which also have elongated fingers, but their closest relatives do not.
“According to the structure of the dental system and skeleton, they resemble modern bats (Daubentonia) of Madagascar and striped cuscus (Dactylopsila) of Oceania, occupying the same ecological niche. Armed and striped cuscus survived on large islands that woodpeckers, the main competitors of these specialized animals, could not colonize. Apatemiids lost in this competitive struggle.
Dactylopsila is the extant striped opossum (not the cuscus), a convergent but unrelated marsupial. “modern bats” is likely a poor Google translation of the original Cyrillic for “modern lemurs”. Many workers considered plesiadapiformes, like Daubentonia, close to primates. In any case, both interrelationships are not supported by the LRT (Fig 2).
From Averinov 2022 continued: “Remains of apatemiids are very rare, which is generally characteristic of forest animals. Apatemiids are well characterized by finds in North America and Europe, but Asian representatives of the group were known only from India. Asiapator onchin, found in the 1970s in the Middle Eocene locality of Khaichin-Ula 3 in the Gobi Desert (Mongolia). The name of the new form is translated as “Asian fatherless orphan” and reflects the singularity of the find and the uncertainty of the relationship of apatemiids among placentals.
In the LRT there is no uncertainty. Adding taxa resolves all phylogenetic problems.
“The jaw belonged to a young animal with an incomplete change of milk front teeth. The features noted on it made it possible to determine the phylogenetic position of Asiapator among Apatemiids and its probable origin from a North American immigrant.”
The juvenile status of Asiapator may be responsible for the appearance of primitive (small) dentition, but a similar excluded taxon, Brachyerix (Fig 1), needs to be included in analysis to make sure.
References Averinov A 2022. Paleogeneic forest pest exterminer: The first representative of wood mammalian – Apatemiid from Central Asia. Paleontological Institute. Borisyak AA editor, Russian Academy of Science. Lopatin AV and Averianov AO 2022. First apatemyid mammal from Central Asia. Journal of Mammalian Evolution 29(1): 129–135. DOI: 10.1007/s10914-021-09574-5, online 01.10.2021.
Sinclairella dakotensis (Jepsen 1934, Early Oligocene, Nebraska, 35mya, Figs 1, 2) is a derived member of the Apatemyidae, within Scandentia (tree shrews) close to the genus Apatemys (Fig 2). All are known from crushed fossils. This clade of squirrel-like, but mouse-sized arboreal mammaals had hyper-robust incisors. Sinclairella had dual sagittal crests, a trait that rarely appears. Unrelated taxa with a similar dual sagittal set of crests includeLeptictis and Megatherium.
Originally Jepsen reported, “[Sinclairella was] immediately recognized as related to the ‘Plesiadapids,’ previously known from the Paleocene and Eocene.”
The large reptile tree(LRT, 1235 taxa) does not support that interrelationship. But remember, Jepsen was writing in 1934. Far fewer fossils back then. No software. No Internet.
A precursor taxon,Microsyops (Fig 2), is currently also mistakenly considered a plesiadapid on the Wikipedia page. That’s one more reason to build your own cladogram. Sometimes wiki-authors pull data from outdated sources.
Jepsen’s description relied strongly on dental traits, as in most mammal papers then and now.
Labidolemuris the oldest (Paleocene), one of the smallest and least derived of the tested Apatemyidae.
Precursor taxa, like Palaechthon and Microsyops, were generally larger than Labidolemur, hinting at phylogenetic miniaturization at the genesis of the Apatemyidae.
Jepsen wrote: “Detail description of many skull characters is inadvisable or impossible because of the crushed condition of the specimen. Further, the degree of specialization is so great that comparisons with most other mammalian skulls appear futile.”
That was then. This is now. More taxa are known. Computers do the rest.
References Jepsen GL 1934. A revision of the American Apatemyidae and the description of a new genus, Sinclairella, from the White River Oligocene of South Dakota. Proceedings of the American Philosophical Society 74(4): 287-305.
Griffin et al. 2022 created a bad chimaera of pterosaur parts (unnatural proportions, lacking fingers, wingtips and feet, Fig 1 middle) to “investigate the ability of a medium-sized ornithocheiraean pterosaur to assume the poses required to launch bipedally or quadrupedally.”
If anyone asks you to do this, politely refuse. Don’t build your own pterosaur from wide-ranging parts of disparate taxa when there are plenty of complete, articulated skeletons to work from.
Yesterday I wrote to lead author Benjamin Griffin: “Thank you for publishing on your and Habib’s pterosaur launch hypotheses.
It would be useful for your models (your figure 1) to have feet and the three free fingers. Lacking those fingers permits your models to apply the wing finger to the substrate – but ichnites indicate that never happens.
The quad launch hypothesis receives much support, but only from workers in South England. Be wary of seeking confirmation from biased co-authors and friends. If your hypothesis can succeed it will do so in the face of withering competition. That competition must come from outside your circle of friends and colleagues.
Griffen et al report, “Our study indicates that a medium-sized ornithocheiraean could assume the poses required to use a quadrupedal launch and, with an additional 10° of hindlimb abduction, a bipedal launch, although further analysis is required to determine whether sufficient muscular power and leverage was available to propel the animal into the air.”
The reason may be due to creating a chimaera, something that never existed. Clearly pterosaurs with such large wings were capable of flight. It’s the even larger ones with smaller wings (all giant azhdarchids) that are troublesome. Based on Griffen’s output (see references below), I hope this is not the only project he has been given by his handlers. He seems to keep publishing on the subject of his hire again and again.
You might remember, back in 2016 U of Bristol put out an advertisement for a student: “The main objective of this proposal is to investigate the effectiveness of the quadrupedal launch [of pterosaurs] and by comparing it with the bipedal launch of birds, test if it was one of the factors that enabled pterosaurs to become much larger than any bird, extant or extinct.”
Note: the professors at U of Bristol did not propose testing the hypothetical quad launch of pteros against the hypothetical bipedal launch of pteros. That took another six years, to the present paper. BTW, Griffen earned a PhD for taking on their assignment.
References Griffen B et al. (six co-authors) 2022. Constraining pterosaur launch: range of motion in the pectoral and pelvic girdles of a medium-sized ornithocheiraean pterosaur. Biological Journal of the Linnean Society, 2022, XX, 1–17. With 7 figures. Online here. Griffin BW, Martin-Silverstone E, Demuth O, Pegas R, Palmer C and Rayfield E 2021. Pectoral and pelvic range of motion constraints on Ornithocheiraen quadrupedal launch. Journal of Vertebrate Paleontology abstracts. Griffin BW, Demuth OE, Martin-Silverstone E and Rayfield EJ 2019. Simulated range of motion mapping of different hip postures during launch of a medium-sized ornithocheirid pterosaur. Journal of Vertebrate Paleontology abstracts. Habib MB 2008. Comparative evidence for quadrupedal launch in pterosaurs. Zitteliana B28:159-166. Witton MP and Habib MB 2010. On the Size and Flight Diversity of Giant Pterosaurs, the Use of Birds as Pterosaur Analogues and Comments on Pterosaur Flightlessness. PLoS ONE 5(11): e13982. https://doi.org/10.1371/journal.pone.0013982
Weekend ‘housekeeping’ at the base of the Placentalia moves Echinosorex(Figs 1, 2), the opossum-like moon rat, closer to the base of the Placentalia in the LRT. The moon rat looks primitive and acts primitive because it is primitive. Moon rats survived the Jurassic by coming out only at night and hiding in leaf litter during the day.
A larger extinct moon rat, Deinogalerix(Figs 2, 4), also moves alongside Echinosorex.
And along with those two, tiny, enigmatic Hapalodectes hetagenesis(IVPP V 5235) is recognized for the first time as a small moon rat taphonomically lacking a premaxilla tip and its teeth. As long-time readers know, I have struggled with identifying those teeth in the data diagram (Fig 3) ever since this taxon’s insertion in the LRT years ago. This understanding brings relief.
Hapalodectes hetangensis (Ting and Li 1987; 4.5cm skull length; Paleocene, 55 mya; IVPP V 5235, Fig 3) This skull was originally and wrongly applied to the Mesonychidae. Here it nests at the base of the moon rat – tenrec – odontocete clade. Note the encircled orbits rotated anteriorly, homologous with ancestral primates.
Echinosorex gymnura (Blainville 1838; length to vent up to 40cm, tail up to 30cm, Figs 1, 2) is the extant moon rat, or gymnure, a small omnivore that looks like a small opossum or rat. Here it nests at the base of the tenrec – odontocete clade.
Deinogalerix koenigswaldi (Freudenthal 1972; Villiera et al. 2013; Late Miocene 10-5mya; skull length 20cm, snout-vent length 60cm) was considered a giant extinct hedge hog, restricted to a Mediterranean island, now part of a peninsula. Here it nests with the moon rat Echinosorex. Giant premolars and tiny molars make the dentition unusual.
Of course, when these small primitive taxa (Figs 1, 2) leave their former nesting sites, the gnawing clade (Glires), reorganizes at its base. If interested in details, see the latest version of the large reptile tree (LRT, 2133 taxa). So few traits presently separate large clades at the base of the Placentalia that small scoring changes still affect the major branches in this clade, as demonstrated above. Scores on basal taxa, are by the definition of evolution, sometimes are transitional between stated traits.
The work continues.
References Freudenthal M 1972.Deinogalerix koenigswaldi nov. gen., nov. spec., a giant insectivore from the Neogene of Italy. Scripta Geologica. 14: 1–19. Villiera B, Van Den Hoek Ostendeb L, De Vosb J and Paviaa M 2013. New discoveries on the giant hedgehog Deinogalerix from the Miocene of Gargano (Apulia, Italy). Geobios. 46 (1–2): 63–75. Ting S and Li C 1987. The skull of Hapalodectes (?Acreodi, Mammalia), with notes on some Chinese Paleocene mesonychids. Vertebrata PalAsiatica. 25: 161–186.
= run time. The time it takes PAUP to process a .nex file increases exponentially with every added taxon.
As an example: Recovering a single tree with 379 taxa: 00:36 seconds Recovering a single tree with 566 taxa: 06:35 minutes Recovering a single tree with 945 taxa: 03:13:00 hours Recovering an unresolved file could go on forever or crash the program, or not. You’ll find out. Learn more about exponents here.
If you have similar run times, relax. It’s normal. Keep plugging away. It’s all good.
Updated September 2, 2022: After reviewing and updating scores in the mammal clade over the last several days… Recovering a single tree with 566 taxa: 01:37 minutes Recovering a single tree with 945 taxa: 59:21 minutes.
Hypothesis: correcting errors, even with a single tree, reduces run times.
Ottoryctes winkleri (Bloch, Secord and Gingerich 2004. UM 7262 middle Wasatchian, Early Eocene, 3.6 cm skull length, Fig 1) is an early shrew close to Microgale (Fig 2) in the large reptile tree (LRT, 2132 taxa). The posteriorly-wide skull lacks cheek arches. The tympanic cavities are further enlarged and raised above the jaw joint. Here the external bulbous bone is restored to match Microgale.
Bloch, Secord and Gingerich 2004 considered only fossil taxa in their analysis. They thought Ottoryctes was a member of the Palaeoryctidae, “thought to have been mole-like burrowing species.” based on cranial and dental material.
The LRT nests Ottorcyctes with the shrew Microgale (Figs 2, 3) with a similar, but smaller elevated tympanic bulla and a long list of other shared traits. This tiny Madagascar shrew mainly inhabits lowland humid and moist montane forests. Burrowing was not reported. When observed in the wild, Microgale cowani behaves cryptically, using all possible sources of cover and avoiding climbing. They build nests with leaves. When washing, individuals sit on their hind legs and stroke both sides of the face with both paws, starting behind the ears and ending at the tip of the nose.
The namesake for the Palaeoryctidae is the EXTREMELY tiny, incomplete Paleocene Palaeoryctes (Matthew 1913, McDowell 1958, Fig 4). It is known from a partial skull and a dentary both with anterior teeth missing. Matthew 1958 reported, “I was forced to conclude that the modern insectivores formed a truly natural group, a conclusion in which I was anticipated by many previous workers,notably W. K. Gregory, who recognized the Lipotyphla as a natural order of mammals.” This statement was made several decades prior to modern software-based phylogenetic analyses. These workers did not realize the broad phylogenetic distance between Leptictis and members of Scandentia (evolving into and at the base of Glires).
Desipite their diminutive sizes, Microgale and Ottorycites are not phylogenetically miniaturized transitional taxa at the genesis of a new clade of vertebrates. Presently they leave no descendants in the LRT. That could change with the next big asteroid strike.
Bloch, Secord and Gingerich report, “The systematic position of Palaeoryctidae is uncertain despite decades of study. We follow Thewissenand Gingerich (1989) in including palaeoryctids in Insectivora (sensu Novacek, 1986) in order to recognize (as they did) a close relationship between taxa included in Palaeoryctidae, Leptictidae, and Lipotyphla.”
Don’t ‘follow’ other authors. Build your own cladogram. Do the work.
Wikipedia cotinues: “From a near-complete skull of the genus Palaeoryctes found in New Mexico, it is known that palaeoryctids were small, shrew-like insectivores with an elongated snout similar to that of the Lepticids. However, in contrast to the latter, little is known about palaeoryctids postcranial anatomy.”
Wikpedia reports, “Lipotyphla is a formerly used order of mammals, including the members of the order Eulipotyphla (i.e. the solenodons, family Solenodontidae; hedgehogs and gymnures, family Erinaceidae; desmans, moles, and shrew-like moles, family Talpidae; and true shrews, family Soricidae) as well as three other families of the former order Insectivora, Chrysochloridae (golden moles), Tenrecidae (tenrecs), and Potamogalidae (otter shrews). However, molecular studies found the golden moles, tenrecs, and otter shrews to be unrelated to the others (these afrothere groups were then put in their own order, Afrosoricida). This made Lipotyphla an invalid polyphyletic order and gave rise to the notion of Eulypotyphla instead, an exclusively laurasiathere grouping.”
Unfortunately this Wikipedia author believes in untenable deep time genomic studies that nest elephants with golden moles and horses with bats. These interrelationships are not supported by the LRT.
Most of the taxa listed above are indeed related to one another and are derived from tree shrews (= Scandentia) that precede members of the gnawing clade Glires. Tenrecs are not related. Shrew tenrecs are not related to the genus Tenrec. Shrew ‘tenrecs’ are just shrews. So, let’s just start calling them ‘shrews’.
Wide gamut trait studies that include fossil taxa, like the LRT, are your only hope for resolving vertebrate interrelationships. Build your own cladogram. It’s a necessary, reliable and powerful tool that should be in every paleontologists’ toolbox.
Also, avoid supertrees. Those never work out well and everyone will know you never studied the taxa.
References Bloch JI, Secord R and Gingerich P 2004. Systematics and Phylogeny of Late Paleocene and Early Eocene Palaeoryctinae (Mammalia, Insectivora) from the Clarks Fork and Bighorn Basins, Wyoming. Contrib Mus Paleontol University of Michigan 31(5):119–154. McDowell SB Jr 1958. The greater Antillean insectivores. Bulletin of the American Museum of Natural History 115(3):113º–214.
Homogalax protapirinus (Wortman 1896, Hay 1899, AMNH 42891, Early Eocene, 50mya, 15cm skull length, Fig 1) nests in the LRT basal to Tapirus the extant tapir (Fig 2). Post-crania indicates a fast cursorial lifestyle. Four molars are present.
References Hay OP 1899. On the Names of Certain North American Fossil Vertebrates. Science 9(225):593-594. Wortman D 1896. Bulletin of the American Museum of Natural History 8: 91.