Carnivora: a misunderstood clade

Traditionally members of the Carnivora
“all have blade-like carnassial teeth – their fourth upper premolar and first lower molar – which bite together to shear through food.”

Sounds like someone out there is trying to “Pull a Larry Martin
by assigning a few traits to define or mark this traditional clade.

UCMP Berkeley correctly notes exceptions, but still manages to “Pull a Larry Martin” when they report, “Carnivores can be told by their enlarged canine teeth, by the presence of three pairs of incisors in each jaw (with rare exceptions), and by the shape of their molar teeth.”

Phylogenetically, not all members have ‘carnasial’ teeth.
Phylogenetically all members of the Carnivora have a last common ancestor in the Middle Jurassic close to extant raccoons (Procyon) and kinkajous (Potos, Fig 1). Thereafter, anything goes. Their ancestors were the ancestors of lions, weasels, wolves, seals, sea lions and several ‘bears’ evolving by convergence in several clades according to results recovered in the large reptile tree (LRT, 2070 taxa, subset Fig 2).

Gene studies have also played havoc
with the clade Carnivora as we learned yesterday. The LRT tests traits.

Figure 1. The cheetah, Acinonyx, enters the LRT today. Note the shorter face, longer vertebral column and longer metatarsals.

Today one and a half new carnivores are added to the LRT.
The speedy cheetah, Acinonyx, enters next to Panthera, the lion. The cheetah is a big cat with a longer, more flexible back (a reversal), longer metatarsals and an even shorter face.

Figure 2. Subset of the LRT focusing on Carnivora.

The half a taxon entering today
is the post-crania of Miacis (Fig. 3), a basal sea lion close to the lineage of cats, dogs in the LRT. Earlier the skull of Macis entered as a taxon alongside short-legged Hyopsodus. These additions, like all additions, shed light where needed. A few scores changed, but the topology remained pretty much the same.

Figure 3. Miacis in situ. This Late Paleocene taxon is basal to sea lions in the LRT and close to the origin of cats and dogs.
Figure 3. Miacis in situ. This Late Paleocene to Late Eocene taxon is basal to sea lions in the LRT and close to the origin of cats and dogs.

If anyone knows of a recent phenomic study of the Carnivora,
please send a citation along. I would like to compare it to the LRT. At present workers seem to be enthralled with genes (references below) and the results are untenable.

References
Agnarsson I, Kunter M and May-Collado LJ 2010. Dogs, cats, and kin: A molecular species-level phylogeny of Carnivora. Molecular phylogenetics and evolution. 54(3):726-745.
Flynn JJ, Finarelli JA, Zehr S, Hsu J and Nedbal MA 2005. Molecular Phylogeny of the Carnivora (Mammalia): Assessing the Impact of Increased Sampling on Resolving Enigmatic Relationships. Journal of Systematic Biology 54:317-337.
Novacek MJ 1992. Mammalian phylogeny: shaking the tree. Nature 365, 121–125. (doi:10.1038/ 356121a0)
O’Leary MA et al. 2013. The placental mammal ancestor and the post–K–Pg radiation of placentals. Science 339, 662–667. (doi:10.1126/ science.1229237)

theguardian.com/science/2017/jul/26/cats-vs-dogs

Civets and cats: Why do they nest together in Wikipedia, but not in the LRT?

Answer:
Wikipedia reports the results of gene studies. The LRT recovers the results of trait studies. Trait studies can include fossil taxa. Gene studies typically cannot include fossils.

Gene studies split cat-like taxa from dog-like taxa within the clade Carnivora
(= Feliformes and Caniformes). According to Wikipedia, “Feliformia is a suborder within the order Carnivora consisting of “cat-like” carnivorans, including cats (large and small), hyenas, mongooses, viverrids, and related taxa.” The clade Caniformia comprise all other members of the Carnivora.

Trait studies, like the LRT, lump cats with dogs within the clade Carnivora
(Fig 1). Hyenas, aardwolves and hesperocyonids are transitional taxa between cats and dogs.

Figure 1. Subset of the LRT focusing on the placental clade Carnivora.

And civets?
In the large reptile tree (LRT, 2069 taxa, subset Fig 1) civets (Fig 2) are very primitive, so they nest far from these two taxa, just outside of Carnivora, close to basal-most placentals and outgroup marsupials and related lemurs.

These distinctly different tree topologies
shed light on the dangers of false positives arising from currently favored genomic analyses. Even so and seemingly oblivious to the red flags, both paleoacademics and Wikipedia writers continue to trust the strange, non-gradual results of deep time genomic studies. Genes have become so popular that few workers test extant taxa using trait studies. Apparently, nobody wants to attempt to falsify deeply entrenched deep time genomic studies. Perhaps this is so because genes work so well in closely related taxa not separated by deep time. It is unfortunate that gene studies break down to such an extent that sometimes bats nest with horses.

According to Wikipedia,
“Civets have a broadly cat-like general appearance, though the muzzle is extended and often pointed, rather like that of an otter, mongoose or even possibly a ferret. Civets are unusual among feliforms, and carnivora in general, in that they are omnivores or even herbivores.”

Just like their most recent marsupial ancestors (Fig 1). The civet, Civetticis (Fig 2) is the most recent addition to the LRT. Phylogenetically civets also precede primates. Chronologically civets appeared in the Early Jurassic.

Figure 1. The civet, Civettictis, enters the LRT today.
Figure 2. The civet, Civettictis, enters the LRT today.

Civettictis civetta
(Schreber 1776; snout rump length = 80cm) is the extant civet. Here it nests between Nandinia and Genetta, not close to cats like Panthera.

The subject of civets, cats and hyenas came up
while viewing a recently published YouTube video on hyenas that used gene studies to lump civets with cats and hyenas. The trait differences are subtle, but many.

Consider the fact
that all tested civets are extant taxa. Given all those dozens of millions of year since the original civets had their genesis in the Jurassic, perhaps it was only natural that they would converge in several ways with the single tested cat, another extant member of the Carnivora with dozens of millions of year to evolve, the lion, Panthera.

References
Schreber JCD 1776. Die Säugthiere in Abbildungen nach der Natur, mit Beschreibungen 3:16.
wiki/Feliformia
wiki/Caniformia

sciencedirect.com/civet

Nagini, described as a ‘snake-like’ Carboniferous ‘amniote’, is not an amniote

Figure 1. Nagini nodule at full scale alongside a skull diagram from Mann, Pardo and Maddin 2022. Colors added here.
Figure 1. Nagini nodule at full scale alongside a skull diagram from Mann, Pardo and Maddin 2022. Colors added here.

Mann, Pardo and Maddin 2022
introduce us to Nagini mazonense (Fig 1), a tiny microsaur taxon found in a Francis Creek Carboniferous nodule exhibiting “extreme axial elongation and corresponding limb reduction.” This taxon “lacks entirely the forelimb and pectoral girdle, thus representing the earliest occurrence of complete loss of a limb in a taxon recovered phylogenetically within amniotes.”

Nagini does not nest ‘within amniotes’ when more taxa are added (Fig 3).

Figure 2. Cladogram from Mann, Pardo and Maddin 2022 suffering from massive taxon exclusion. Colors added here. Compared to figure 3.

The authors made several phylogenetic mistakes
due to taxon exclusion. Nagini and its sisters (e.g. Brachydectes, Fig 4) are not amniotes in the fully resolved large reptile tree (LRT, 2066 taxa. subset Fig 3). Instead they are highly derived microsaurs closer to similar elongate and limbless caecilians and their nearly limbless kin.

Caecilians in the LRT (Fig 3) are not related to frogs and salamanders as they are in the Mann, Pardo and Maddin cladogram (Fig 2).

The basalmost amniotes in the LRT (Figs 3, 5) are not included in the Mann, Pardo and Maddin cladogram (Fig 2).

The basalmost tetrapods and dozens of other taxa in the LRT (Fig 3) are not included in the Mann, Pardo and Maddin cladogram (Fig 2).

Figure 3. Subset of the LRT focusing on basal tetrapods, microsaurs and basal reptiles.
Figure 3. Subset of the LRT focusing on basal tetrapods, microsaurs and basal reptiles. The LRT is completely resolved, includes more pertinent taxa and nests Brachydectes and kin close to similar caecilians within Microsauria. The gray triangle points to Brachydectes, a close relative of Nagini, far from the amniotes (= Reptilia). The basal taxon in Archosauromorpha is Gephyrostegus.

Don’t try to grab headlines by claiming to have a Carboniferous amniote
when you have a microsaur. Don’t cherry-pick taxa and omit basal amniotes in your study of basal amniotes and microsaurs. Taxon exclusion is the number one problem in paleontology.

Figure 2. Brachydectes elongatus (Lysorophus tricarinatus) from Carroll and Gaskill 1978 and Wellstead 1991 with colors and new bone identities added.
Figure 4. Brachydectes elongatus (Lysorophus tricarinatus) from Carroll and Gaskill 1978 and Wellstead 1991 with colors and new bone identities added. This taxon is closely related to Nagini (Fig 1).

Finding a fossil is step one.
Identifying a fossil is step two. You can only identify a fossil by comparative morphology and phylogenetic analysis. You can only compare morphologies by including a wide gamut of taxa, some closely related, others not. So don’t borrow and don’t cherry-pick. Do the work. More more pertinent taxa always improves a cladogram. More taxa will improve your understanding of tetrapod and reptile evolution. At present, Mann, Pardo and Maddin 2022 lack demonstrate they lack that understanding due to taxon exclusion.

Figure 2. Eusauropleura to scale with ancestral and descendant taxa including Eucritta, Utegenia, Silvanerpeton and Gephyrostegus, the last common ancestor of all reptiles.
Figure 5. Eusauropleura to scale with ancestral and descendant taxa including Eucritta, Utegenia, Silvanerpeton and Gephyrostegus, the last common ancestors of all reptiles. Note the long, strong legs. Other than Eucritta, these taxa were omitted from Mann, Pardo and Maddin 2022.

According to the commentary by co-author Mann 2022
“we know comparatively little about whether the earliest amniotes were capable of achieving the same range of diverse body plans and ecologies seen in modern amniotes.”

This is a common tactic among paleo writers, telling the reader how little is known. This sets up their heroic entrance. In this case what Mann reports is incorrect when more taxa are added to analysis, as in the LRT. This is data readily accessed for free online.

“Historically early amniotes were thought to have all been roughly similar in body shape and ecology, with only some variation in feeding and display structures, with amniote morphological diversification really kicking into high gear by the late Permian with the diversification of therapsids and then of diapsid reptiles.”

Early amniotes (Fig 5, ironically missing from the Mann, Pardo and Maddin cladogram, Fig 2) are indeed roughly similar in body shape and ecology.

“One of the important ways in which amniotes can diversify is through modifications in limb morphology including the reduction or even complete loss of limbs.”

When more taxa are added this doesn’t happen in basal amniotes, only in highly derived microsaurs close to caecilians. If a large morphological gap is present in your cladogram, that’s a sign to add taxa. Mann is constructing his own scenario by cherry-picking taxa.

“Recently, a diverse group of early tetrapods known as the Recumbirostra, named after their shared adaptation of recumbent snouts (likely for headfirst burrowing), have risen to prominence in research on the origin of amniotes with several recent studies regarding the group as one of the earliest diversifications of reptiles.”

The LRT does not support this hypothesis of interrelationships. Adding taxa splits Recumbirostra apart from Reptilia. Early Carboniferous reptiles, getting used to their new terrestrial niche, improve and lengthen their limbs (Fig 5), just the opposite of the Mann, Pardo and Maddin hypothesis.

“In general, the presence of diverse limb-reduced and axially-elongated forms, including forms like Nagini with complete forelimb loss, at or near the base of Amniota supports the idea that limb reduction and axial elongation is an adaptive mode ancestral to amniotes.”

Just the opposite (see above paragraph). The legs and toes become stronger in basal amniotes (Fig 5) clambering around their swampy-to-dry environs where their dry terrestrial amniotic eggs are deposited.

A valid phylogenetic context demonstrating a gradual accumulation of derived traits is paramount. Don’t write another paper without one. I hate to see yet another new myth grow when simply adding taxa readily falsifies Mann’s conclusions.

References
Mann A, Pardo JD and Maddin HC 2022. Snake-like limb loss in a Carboniferous amniote. Nature Ecology and Evolution https://doi.org/10.1038/s41559-022-01698-y

Mann 2022 commentary
nature.com/posts/a-farewell-to-arms

A review of monotreme evolution that omits several monotremes

Flannery et al. 2022 discuss
Early Cretaceous Teinolophus trusleri, a tiny mandible taxon (Fig 1, NVM P229408), which they described as, “the oldest known monotreme”. They write, “Teinolophos trusleri likely possessed an electro-sensitive and/or mechano-sensitive ‘bill’ or ‘beak’, which we suggest evolved for insectivory in seasonally dark Early Cretaceous polar forests.”

The LRT (subset figure 3) recovers at least four much older monotremes, three from the Jurassic and one from the Late Triassic: Brasilitherium (Fig 2).

Among LRT taxa, untested Teinolophus is similar to
Brasilitherium (Fig 2). Both share two anteriorly oriented incisor alveoli, a small canine alveolus, widely spaced anterior teeth, a small and elevated retroarticular process, a small coronoid process and several other distinctive traits. Sinodelphys (Fig 1) also shares several traits. It is larger and has more tightly packed teeth because it is more primitive, closer to the basalmost mammal in the LRT, Megazostrodon.

Rich et al. 2016
“redescribed and reinterpreted [Teinolophos] here in light of additional specimens of that species and compared with the exquisitely preserved Early Cretaceous mammals from Liaoning Province, China.”

Rich et al. created the reconstruction in figure 1 by creating a chimaera of the holotype and the additional specimens. The frame 2 overlay shows the chimaera is not a perfect match for the synchotron X-ray tomograph at the top of figure 1.

Rowe et al. 2008
labeled Teinolophus ‘the oldest platypus’.

By contrast in the LRT Early Cretaceous Akidolestes nests with Ornithorhynchus, making Akidolestes the oldest platypus. Traditional sisters to Akidolestes include Earliest Cretaceous Zhangheotherium (basal to pangolins in the LRT) and Early Cretaceous Maotherium (a cynodont sister to another Early Cretaceous cynodont, Origolestes). So these traditional sisters are spread over a wide patch of derived synapsids in the LRT rather than nesting as sisters. Be careful with convergent molar shapes (Fig 4).

Figure 1. Early Cretaceous Teinolophus mandible and molars. This is not the oldest monotreme in the LRT. The artistic restoration has some traits not typically found in monotremes, like that tall coronoid process, that low retroarticular process and that spherical glenoid joint. See figure 2 for several comparable mandibles, especially Brasilitherium.

Flannery et al. remark,
“Teinolophidae represents the oldest recognized family of monotremes followed chronologically by Kollikodontidae, Steropodontidae, Ornithorhynchidae, and Tachyglossidae.”

Flannery et al. list 13 monotreme taxa many based on teeth. Other than Tachyglossus and Ornithorhynchus (Fig 2) the Flannery et al. taxon list and the LRT do not overlap. Brasilitherium and Megazostrodon (the last common ancestor of all LRT mammals) are traditionally considered pre-mammal cynodonts. Sinodelphys is traditionally considered a marsupial. Perhaps that’s why they are not mentioned in the Flannery et al. 2022 text.

Figure 1. Brasilodon compared to Kuehneotherium, Akidolestes and Ornithorhynchus, the living platypus.
Figure 2. Brasilitherium compared to Kuehneotherium, Akidolestes and Ornithorhynchus, the living platypus.

The authors write,
“Monotremes were long classified within the subclass Prototheria, together with morganucodonts, docodonts, triconodonts and multituberculates (Kemp 1983). Prototheria is now recognized as a grade rather than a clade (Kemp 1983; although see Sereno 2006 and O’Leary et al. 2013 for dissenting views), prompting re-classification within a more inclusive Jurassic-Cretaceous Gondwanan infraclass Australosphenida, which also included the endemic Australian Ausktribosphenidae (Luo et al. 2001, 2002).”

Figure 3. Subset of the LRT focusing on basal mammals including monotremes. The oldest monotreme here is from the Late Triassic with earlier origins. The last common ancestor of all mammals, Megazostrodon, is known from a late survivor in the Jurassic.

Definitions from Wikipedia
Monotremes (Bonaparte 1837) are prototherian mammals of the order Monotremata. They are one of the three main groups of living mammals, along with placentals (Eutheria) and marsupials (Metatheria).

The LRT recognizes the monophyly of the Monotremata with the list of taxa in figure 2.

Prototheria (Gill 1872) is a subclass to which the orders Monotremata, Morganucodonta, Docodonta, Triconodonta and Multituberculata have been assigned, although the validity of the subclass has been questioned.

The LRT does not recognize the monophyly of the Prototheria. This list of members is a junior synonym for Mammalia because it includes marsupials (e.g. Morganucodon) and placentals (e.g. multituberculates).

Figure 3. Mammal tooth evolution alongside odontocete tooth evolution, reversing the earlier addition of cusps.
Figure 4. Mammal tooth evolution alongside odontocete tooth evolution, reversing the earlier addition of cusps.

I remind workers
to employ a wide gamut of taxa represented by skeletons, like the LRT does. Don’t rely on citations and consensus (e.g “long classified”, “now recognized”, “dissenting views”). Dental traits can also converge and reverse (Fig 4). Old traditions and current textbooks can mislead. Let your software tell you how clades lump and separate. Don’t rely on others. With your own cladogram you will be able to report clade membership with authority and without “Pulliing a Larry Martin.” In other words, you won’t be fooled by a few ‘key traits’ too easily affected by reversals. And you won’t omit in-group taxa.

References
Flannery TF et al. (5 co-authors) 2022. A review of monotreme (Monotremata) evolution. Alcheringa: an Australian Journal of Palaeontology. https://doi.org/10.1080/03115518.2022.2025900
Rich TH et al. 2016. The mandible and dentition of the Early Cretaceous monotreme Teinolophos trusleri. Alcheringa 40.
Rowe T, Rich TH, Vickers-Rich P, Springer M and Woodburned MO 2008. The oldest platypus and its bearing on divergence timing of the platypus and echidna clades. Proceedings of the National Academy of Sciences USA 105, 1238–1242.

wiki/Akidolestes
wiki/Teinolophos
wiki/Prototheria
wiki/Monotreme
wiki/Phylogenetics

Reasoning by first principles removes the impurity of assumptions and conventions. So much of what we believe is based on some authority figure telling us that something is true.

Bisconti and Carnevale 2022 discuss the origin of baleen whales while omitting the ancestors of baleen whales

It’s a long-standing myth
that the traditional clade ‘Cetacea’ is monophyletic. Van Valen 1968 suspected the diphyly of whales back in 1968. The large reptile tree (LRT, 2065 taxa) recovered three origins for ‘whales’. Right whales arose from Desmostylus (Fig 1), rorquals from Behemotops (Fig 2) and toothed whales from extinct Pakicetus and its ancestors, echo-locating extant tenrecs (Fig 3).

Figure 1. Taxa in the lineage of right whales include Desmostylus, Caperea and Eubalaena. The tiny bit of jugal posterior to the orbit (in cyan) is found in all baleen whales tested so far. The frontals over the eyes are just roofing the eyeballs in Desmostylus, much wider in Caperea and much, much longer in Eubalaena.
Figure 1. Taxa in the lineage of right whales include Desmostylus, Caperea and Eubalaena. The tiny bit of jugal posterior to the orbit (in cyan) is found in all baleen whales tested so far. The frontals over the eyes are just roofing the eyeballs in Desmostylus, much wider in Caperea and much, much longer in Eubalaena.

Bissconti and Carnevale 2022 perpetuate this myth
by excluding the recovered ancestors of baleen whales in the LRT (Figs 1, 2) while trying to jam archaeocetes together with mysticetes. Sadly, this is something all other current whale workers are also doing. Convergence in the two clades seems to make this possible, but taxon omission is still the problem. Adding taxa is all it takes to separate them.

Figure 1. Rorqual evolution from desmostylians, Neoparadoxia, the RBCM specimen of Behemotops, Miocaperea, Eschrichtius and Cetotherium, not to scale.
Figure 2. Rorqual evolution from desmostylians, Neoparadoxia, the RBCM specimen of Behemotops, Miocaperea, Eschrichtius and Cetotherium, not to scale.

Taxon exclusion remains the number one problem
in paleontology. Don’t cherry-pick taxa, even if you have the approval of your peers to do so.

Figure 3. Taxa preceding Pakicetus in the LRT. Other workers offer hippos, cattle and pigs as ancestors. Tenrecs echolocate their prey and have torsioned skulls in order to do so.

Some readers think the LRT is the problem
because it recovers new hypotheses of interrelationships overlooked by “thousands” of prior workers, all of them professionals and PhDs. Unfortunately, I have to remind these errant readers that their beef should be with the ones who overlooked actual ancestors by taxon exclusion, not with the LRT, which minimizes taxon exclusion. Also to remember that evidence always trumps authority, tradition and textbooks. That’s the science we all believe in, signed up for and swore to defend.

References
Peters D unpublished ms. The triple origin of whales. ResearchGate.net
Van Valen L 1968. Monophyly or diphyly in the origin of whales. Evolution. 22 (1):37–41.
Various authors mistakenly discuss the origin of baleen here due to taxon exclusion.

reptileevolution.com/reptile-tree.htm

The origin of two sets of antennae in crustaceans

Wkipedia reports,
“Crustaceans bear two pairs of antennae. The pair attached to the first segment of the head are called primary antennae or antennules. This pair is generally uniramous, but is biramous in crabs and lobsters and remipedes. The pair attached to the second segment are called secondary antennae or simply antennae.”

“Many crustaceans have a mobile larval stage called a nauplius, which is characterized by its use of antennae for swimming. Barnacles, a highly modified crustacean, use their antennae to attach to rocks and other surfaces.

See figure 1 for a selection of crustaceans, at least one of which uses its second set of antennae to wave floating food particles into its mouth. We looked at these crustaceans earlier.

Figure 1. A selection of crustaceans arising from trilobites. Note: crustaceans go without antennae for several steps in this transitional series. Then limbs evolve antennae-like traits. See figure 2 for how that happens.

Derby 2021 wrote:
“the antennule is a complex and dynamic sensory-motor integrator that is intricately engaged in most aspects of the lives of crustaceans.” Derby borrows from Cong et al. 2014 who presents a hypothetical origin for two sets of antennae in crustaceans.

Cong et al. 2014
used a hypothetical transitional ‘stem euarthropod’ to show how the large ‘frontal appendages’ (= thick antennae) in a radiodont, like Anomalocaris hypothetically migrated from the anterior of the animal and hypothetically shrank in size to border the ventral mouth. At the same time, a set of first antennae hypothetically erupted from the first body segment, then two pairs of antennae hypotheticially erupted from the second body segment. No precursor structures are shown or considered because…

Trilobites, Triops and horseshoe crabs are not mentioned in the text.

We looked at the origin of trilobites
from flatworms and anomalocarids earlier here.

Conge et al. described “anomalocarid frontal appendages”:
“These structures are variably homologized with jointed appendages of the second (deutocerebral) head segment, including antennae and ‘great appendages’ of Cambrian arthropods, or with the paired antenniform frontal appendages of living Onychophora
and some Cambrian lobopodians.”

Here those ‘great appendages’ are homologous with trilobite antennae AND velvet worm antennae, NOT crustacean or insect antennae.

Figure 1. Limulus, Pseudokianda and Triathrurus in ventral view. Triops in ventral view. Color changes show trilobite and crustacean homologies.
Figure 2. Limulus, Pseudokianda and Triathrurus in ventral view. Triops in ventral view. Color changes on Triops show trilobite and crustacean homologies. The feeding area appears as a red blinking streak. Here the first two feeding limbs of the trilobite and horseshoe crab transform to become the first and second antennae of the basal crustacean, Triops.

The basal crustacean Triops
together with the horseshoe crab, Limulus, and two trilobites, Triarthrus and Pseudokianda (Fig 2) appear to shed light on the origin of the two sets of antennae in crustaceans.

Step one: horseshoe crabs
(= Limulus, Fig 2) lack antennae of any sort.

Step two: in the basal crustacean Triops
(Fig 2) traditional anomalocarid and trilobite antennae are also absent.

Step three:
In Triops the first two limb segments are co-opted to become new crustacean antennae (Fig 2). At this stage both retain limb-like joints and both extend beyond the length of the other limbs. Moreover, limb 2 (= second antenna) splits distally as in certain, but not all crustaceans (Fig 1).

Some crustaceans have the traditional ability
to sense the environment with both sets of antennae (Fig 1). Other crustaceans use the large second antennae to wave floating food into the central oral area (e.g. Cyzicus in figure 1 top) while also sensing the environment. Both traits are retained from trilobite ancestors in which the anterior limbs surrounded the central oral area. These are real co-opted structures, not novel hypothetical structures.

This is how a primitive structure
evolves through generations from one morphology into another. We recently covered something similar: the origin of the telson in trilobites from a primitive dorsal spine.

Figure 2. The triopsid Lepidurus (photo above) retains a tiny telson. Triops (diagram below) retains a mere vestige telson, hardly visible.
Figure 3. The triopsid Lepidurus (photo above) retains a tiny telson. The triopsid Triops (diagram below) retains a mere vestige telson, hardly visible. Note the similarity of Triops to Limulus (the horseshoe crab) and trilobites like Pseudosaukianda (Fig 1).

Taxon exclusion remains the number one problem in paleontology.
Why did Cong et al and Derby omit trilobites, horseshoe crabs and Triops from their studies on crustacean antennae? Here these are key taxa that document the evolution of limbs into antennae in crustacea from trilobite ancestors.

This hypothesis of morphology is more evidence for the novel hypothesis
that some trilobites are not extinct — if you follow the tenets of monophyly.

Figure 4. Middle Cambrian Habelia optata from Aria and Baron 2017 and colored here. This taxon appears to share more traits with krill than scorpions. Note the lack of any sort of antennae.

PS
Aria and Baron 2017 considered Middle Cambrian Habelia optata (Figs 1, 4) a member of the Chelicerata, basal to spiders and scorpions. Here (Fig 1) Habelia appears to share more crustacean traits, closer to shrimp and krill. Note the lack of antennae, as in horseshoe crabs like Limulus (Fig 2). Of course, this is prior to analysis, still just gathering data.

References
Aria C and Caron J-B 2017. Mandibulate convergence in an armoured Cambrian stem chelicerate. BMC Evolutionary Biology (2017) 17:261 DOI 10.1186/s12862-017-1088-7
Cong P, Ma X, Hou X, Edgecombe GD and Strausfeld NJ 2014. Brain structure resolves the segmental affinity of anomalocaridid appendages. Nature 513: 538–542.
Derby CD 2021. The Crustacean Antennule: A Complex Organ Adapted for Lifelong Function in Diverse Environments and Lifestyles. Biol Bull 240:67–81.

wiki/Antenna_(biology)
wiki/Lepidurus_apus
wiki/Habelia


The origin of the telson in trilobites

Some trilobites have a telson
(Figs 1, 2). Others do not (Fig 2). Those that do not have a telson often have a fused pygidium (= posterior plate). Still others have an unfused pygidium with a dorsal spine. Still others have a very small unfused pygidium and the dorsal spine has grown to the proportions of a telson. Still others lose the pygidium entirely and have a telson instead.

That’s the origin of the telson in trilobites. Details and images follow.

Anonymous Reader (his choice of a pseudonym)
insisted that trilobites did not have a telson and backed it up with published images (Fig 2 lower row) of several trilobite posteriors with a dorsal spine along with a scan of text (Fig 3) from early trilobite describers. Anonymous Reader had an argument and backed it up with evidence. That’s an excellent way to argue. All too rare here. Unfortunately Anonymous Reader also included a few irrational and ad hominem statements. All too common here.

Suggestion: Write down everything you feel. Then, in a second draft, edit out all your feelings and stick to the business and evidence of science.

Anonymous Reader did not realize
that the evidence he presented actually showed how the dorsal spine evolved to become a telson, thereby undermining his efforts. The primitive pygidium lost fusion, then lost segments, then finally disappeared (Fig 2). Provided that data as a resource was not his intention, but as you’ll see, that was the unintended consequence.

Figure 1. Image published earlier showing a trilobite with a telson (left) and a horseshoe crab with a telson (right).

Anonymous Reader wrote:
“I will point out again here that the entire premise of your arthropod concept so far is flawed, because you are basing it on a misunderstanding of a fake trilobite fossil you found on google images. Trilobites did not have a telson, the thing you highlighted as a telson on the forgery Pseudosaukianda is an axial spine from the thorax that hangs over the tail (because it is a redlichiid). Everything you are presenting has been already considered, and was very quickly debunked or disproved.”

Unfortunately, no evidence was presented by Anonymous Reader to back up his claim that the fossil in figure 1 was a fake or a forgery. Contra his claim, hundreds of online images of Early Cambrian trilobites have a telson (click here).

To Anonymous Reader’s point, the trilobite ‘telson’ is indeed a former axial spine from the thorax (see figure 2), but it cannot hang over a ‘tail’ (= pygidium) that is no longer present. The pygidium shrinks and disappears in certain lineages of derived trilobites (Fig 2).

My initial private email reply:
Hi [Anonymous Reader], I will publish your comment if you insist. Before you decide, please take a look at the following Google page of images for the trilobite Olenellus, just one genus of several with a telson.

You can click on this link to see for yourself several dozen Olenellus trilobites with a telson. Or take a peek at Olenellus in figure 2, far right, or Pseudosaurkianda in figure 1, left.

Figure 2. Upper row: Trilobites without a spine or telson. Pygidium in green. Lower row: Series of trilobite posteriors with a developing spine (red) and a shrinking unfused pygidium culminating in the loss of the pygidium in Olenellus at far right. At this point the ‘spine’ has evolved to become the ‘telson’. Unfused pygidium images at lower left provided by Anonymous Reader. Other images found online. Colors added here.

Anonymous Reader wrote a day later:
“Yes, I insist, so long as you do not twist my words and publish it as is. With all due respect, you have made the same mistake here – you have not any research. You have found images of trilobites on the google search page (how you came across the names in the first place I don’t particularly know), yes, but that is the whole extent of it. In fact, I’m unsure you’ve even studied the images themselves. At least with Olenellus, the fossils aren’t artificially reconstructed to sell, as many less common trilobites are (such as Pseudosaukianda).”

“Olenellus is also a redlichiid, like Pseudosaukianda. What you are again calling a telson is, again, just a spine projecting from the thorax over a relatively mundane pygidium (the terminal section of the trilobite exoskeleton, “the tail”). It covers the segments behind it well, but yet again, this “telson” isn’t on the tail. It’s just a spine on the back.”

“As with Pseudosaukianda, you have only gone onto google images for research, found the first few images, and went into it assuming that everybody else was wrong, and that only you can see clearly.”

“Olenellus has been known for nearly a century and a half. The proposition that this spine represented a telson was considered, and then easily refuted. Your theory was disproven by Walcott and others more than 100 years ago. In the future, I suggest primary research (using Google Scholar, it took less than 30 minutes to compile the image attached below), and a less self-centred approach (in which, again, you consistently believe you are the only one able to see clearly, and that the research, struggle, and debate of the last several centuries was done entirely in error).”

As you can see, Anonymous Reader has quite a knowledge of trilobiites, but insists the telson extending posteriorly in Pseudosaukianda and Olenellus is “just a spine on the back”. He is overlooking the fact that there is no longer a “back” in these taxa. Instead that spine now matches the size, placement and morphology of the telson in Limulus, the horseshoe crab (Fig 1 right). The unfused pygidium shrinks and disappears.

Anonymous Reader concluded:
“This attached image [Fig 3] includes select passages from papers older than 100 years. The fossils depicted are not exclusively Olenellus, but at the minimum, are extremely closely related (one species evolving directly into another without a common ancestor, in some cases).”

Figure 3. Complete text with highlights sent from reader Anonymous Reader. In the third (white bkg) paragraph, the author, familiar with the telson in Olenelllus, noted “instead of being a telson” in the form essentially similar to Olenellus, “a thoracic segment with a long median spine” and posterior to it ten more segments and a plate-like pygidium, likely describing the specimen in figure 2, far left, bottom row.

My second private email reply to Anonymous Reader:
“You’ve shown me how the spine (= telson) evolved from segments just prior to the pygidium, as they are in trilobites with a telson. Then the pygidium disappears. You’ve shown me the step-by-step process. [Fig. 2] Note: trilopbites with a telson (spine) lack a pygidium. This is called homology and evolution. I will publish the materials you’ve sent + your comments, unless you want to stop me in the next 24 hours. I’d like to help you avoid the embarrassment of a false accusation.”

Is it true that I go into an image search
“assuming everyone else is wrong and that only I can see clearly?” No. Like many of you, I am a lifelong learner. I will venture a guess that Anonymous Reader cannot read minds (phylogenetic bracketing was used to determine this) and if he can by exception, he should probably take the advice to avoid that vice. I go into an image search seeking data. If data happens to support a new hypothesis over a traditional hypothesis, it’s been my job for the last 12 years to report results. That’s the scientific method devoid of academic politics: discover, research, describe, respond to feedback.

Taxon exclusion is not the problem this time.
In this case nature co-opted an existing dorsal spine to evolve into a long, posterior telson while the pygidium beneath it lost fusion, lost segments, then disappeared step-by-step over generations. The homology of the dorsal spine and posterior telson should have been recognized decades ago. This shouldn’t be the first time for this homology to be announced, but perhaps it is just that, judging by the reports of several current online authorities:

From the AMNH webpage on trilobites:
Telson: A pronounced tail spine emanating from the pygidium.”

That is incorrect as you can see from figure 2. The spine/ telson and pygidium are separate elements arising from separate sections of the trilobite.

From the Wikipedia Trilobite page:
“The pygidium is formed from a number of segments and the telson fused together.”

This is incorrect as you can see from figure 2.

From the Wikipedia Telson page:
“The telson is the posterior-most division of the body of an arthropod. Depending on the definition, the telson is either considered to be the final segment of the arthropod body, or an additional division that is not a true segment on account of not arising in the embryo from teloblast areas as other segments. It never carries any appendages, but a forked “tail” called the caudal furca may be present. The shape and composition of the telson differs between arthropod groups.”

Correction: The telson, as seen here (Fig 2), is not the posterior-most division until it is the posteriormost division once the pygidium becomes a vestige then disappears. Query: Which embryo? Clarification: a forked ‘tail’ is not a telson. This sentence should be edited out because, as the author notes, a telson ‘never carries any appendages.’

From Encylcopedia.com
“The prominent, backward-pointing spine at or near the rear extremity of a trilobite (Trilobita) is also called a telson, although it may or may not be the equivalent of a true telson.”

Correction: If a trilobite has a posterior spine, it is indeed a true telson, derived from a former dorsal spine arising from the last thorax segment following pygidium reduction and disappearance. Homology is the key to understanding how one trait or one organism evolves to become another.

This appears to be a novel hypothesis of homology.
If not, please provide a citation so I can promote it here. This homology is something that should have been reported decades ago. Thanks are due to ‘Anonymous Reader’ for sending the pertinent images used in this post.

References
wiki/Trilobite
wiki/Telson
amnh.org/the-trilobite-files/trilobite-terminolgy

The gibbon, Hylobates, enters the LRT alongside other bipedal hominoids

Hylobates lar
(Linneaus 1771, Figs 1, 2) is the extant gibbon, a long-legged primate with even longer arms. Adult gibbons have a rather flat face, like that of a young chimp, an adult Ardipithecus (Figs 3, 4) and an adult human, rather than the protruding rostrum of an adult chimp (Figs 5, 8).

Traditionally, the lineage that led to extant gibbons
was considered the earliest hominoid lineage to diverge from those that led to the great apes and humans. As JaneGoodall.org reports (Fig 6a), gibbons nest between Old World monkeys and big hominoids (= hominids). Workers reported this happened about 17 million years ago based on genomic studies. Recent “geometric, morphometric and phylogenetic comparative methods” (Rocatti and Perez 2019) confirmed the separation of gibbons from other apes + humans.

Today Hylobates enters the LRT at a non-traditional node
based on the same skeletal traits scored for every other taxon in the LRT, from birds to fish.

Figure 1. Skeleton of Hylobates, the extant gibbon. Note metacarpal 2 and metatarsal 2 are the longest in each series. Like humans, this is not a knuckle-walker and is specialized for its present-day niche. No doubt ancestors had more plesiomorphic proportions.

Don’t freak out.
Here in the large reptile tree (LRT, 2065 taxa, subset Fig 6b) Hylobates nests closer to Ardipithecus (Figs 3, 4) + Homo than to Macaca, Proconsul, Pan (Fig 5) and Gorilla. The LRT uses no traits specific to hominoids (perhaps a shortcoming in this case), yet remains fully resolved. Gross morphology is what the LRT scores, not subtle dental traits.

Figure 2. Skull of Hylobates in three views. Colors added here. Compare to Ardipithecus in figure 3. Those long canines are reduced in Ardipithecus.

Deletion of Ardipithecus from the LRT
does not change the remaining tree topology (subset Fig 6b).

The LRT results appear to be indicating
that gracile gibbon morphology is more plesiomorphic (= representative of the basal bauplan) than that of more robust chimps and gorillas. Likewise, humans and their kin are also more plesiomorphic despite a few, well-known evolutionary derivations.

Figure 3. Skull of Ardipithecus from Jay Matterness. Compare to Hylobates in figure 2.

Hylobates lar
(Linneaus 1771) is the extant gibbon. Today gibbons are jungle dwellers specializing in brachiation (= swinging rapidly from vine to branch beneath their outstretched arms). This is a new mode of locomotion for tetrapods. By convergence, New World spider monkeys (genus: Ateles) also brachiate. On the ground, gibbons run bipedally (see Fig 7 and attached video). This is distinct from chimps and apes that run quadrupedally with knuckles in contact with the substrate.

Current hypotheses on human origins agree
that bipedal running was an early innovation. This behavior is only shared with gibbons among the hominoids. Bipedal locomotion is enhanced and enabled by the gracile proportions of gibbons and humans.

Figure 4. Skeleton of Ardipithecus from Jay Matternes.
Figure 4. Skeleton of Ardipithecus from Jay Matternes. Note the long arms and legs, along with the upright posture, gracile build and gibbon-like skull.

Ardipithecus ramidus
(White et al. 1995; 4.4 and 5.6 mya, Late Miocene, early Pliocene, 4’11” tall) was preceded by Hylobates and succeed by Homo in the LRT (subset Fig 6b).

Ardipithecus was the first genus in human ancestry to habitually walk upright, predating Australopithecus by a million years. Ardipithecus incorporated an arboreal grasping hallux or big toe, reduced canine teeth and a smaller brain size like that of the modern chimpanzee. The skull was noticeably smaller than either Proconsul or Australopithecus, but similar in proportion to Hylobates. The eye sockets were relatively much larger, as in Hylobates.

The teeth of Ardipithecus lack large canines. It was probably an omnivore, like Hylobates. Without large display canines, Ardipithecus society probably had reduced male-to-male conflict, increased pair-bonding, and increased parental investment, like Hylobates.

The pelvis was bowl-shaped, like that of an australopithecine or human, not like Hylobates. The knees were kept beneath the body, like Hylobates, not bowed out like a chimp. Ardipithecus feet are suited for walking, but could still grasp trees, though not as well as a chimp or gibbon.

When walking upright fertility signals become hidden. Gibbons, like humans, do not have the exaggerated menstrual cycle swelling signaling fertility, as seen in chimps and other quadrupedal anthropoids.

Figure 5. Skeleton of Pan, the chimpanzee.
Figure 5. Skeleton of Pan, the chimpanzee in a typical quadrupedal pose, knuckle-walking like Gorilla, the gorilla, not like Hylobates, the more gracile, bipedal gibbon. See figure 7.

According to Wikipedia,
Ardipithecus is a genus of an extinct hominine that lived during the Late Miocene and Early Pliocene epochs in the Afar Depression, Ethiopia. Originally described as one of the earliest ancestors of humans after they diverged from the chimpanzees, the relation of this genus to human ancestors and whether it is a hominin is now a matter of debate.”

Figure 6a. Traditional primates cladogram from janegoodall.org. Note the placement of gibbons between monkeys and apes + humans. Compare to the more complex cladogram from the LRT in figure 6b.

According to Wikipedia,
“Gibbons differ from great apes in being smaller, exhibiting low sexual dimorphism and not making nests. Gibbons frequently form long-term bonds. Gibbons’ fur coloration varies from dark-to light-brown, and any shade between black and white. One unique aspect of a gibbon’s anatomy is the wrist, which functions something like a ball-and-socket joint, allowing for biaxial movement.”

As in humans.

Figure 6b. Subset of the LRT focusing on primatess. Second frame shows additional steps when paired taxa are forced together. Not much separates certain taxa at present, but the LRT remains fully resolved.

Gibbons do not swim.
Therefore large rivers isolate clans leading to diversification.

Figure 7. Two images of bipedal gibbons. This is the first ‘step’ in human evolution, perhaps in a last common ancestor of gibbons and humans, apart from chimps + apes, according to the LRT.

Fossil gibbons are rare.
The oldest fossil gibbon (Ingicco, de Vos and Huffman 2014) is a partial femur from Lower/Middle Pleistocene (0.8 mya), East Java, Indonesia. The authors report, “as we show here, Trinil 5703 represents the oldest known presence of small apes in insular Southeast Asia [SEA], and provides further evidence of ever-wet forest habitat in an area of Homo erectus occupation.”

Figure 8. Gracile gibbons and humans appear to be more similar overall, distinct from more robust chimps and gorillas. Each has undergone its own evolution from a more plesiomorphic last common ancestor, like Macaca and Proconsul in figure 6.

These hypotheses and results from the LRT need to be confirmed or refuted
with a similar taxon list using phenomic scores for the cranium and post-cranium, not genomic scores, which tend to produce false positives often based on geography (e.g. Afrotheria).

The present LRT scores may indicate convergence
rather than homology. This is a subject worthy of further study.

‘Lucy’ the australopithecine cannot be added to the LRT
because too little is known of the specimen.

Here is a YouTube video showing gibbons in action
as they brachiate through their enclosure, then run bipedally, distinct from chimps and gorillas.

YouTube video of gibbons running bipedally around their enclosure.

Added a few hours after publication
Alba et al. 2015 described a small-bodied ape, Pliobates, from the Miocene that “may have contributed more to the evolution of the hominoid lineage than previously assumed.” The authors nested it basal to all hominoids and not close to hominids or hominines.
From the introduction: “This has led to the assumption that hylobatids are a dwarfed lineage that evolved from a larger-bodied and more great ape–like common ancestor with hominids (great apes and humans).”
From the rationale: “Here we describe a new genus of small-bodied (4 to 5 kg) ape from the Miocene (11.6 Ma), discovered in [the] northeast Iberian Peninsula (Spain), that challenges current views on the last common ancestor of extant hominoids. This genus is based on a partial skeleton that enables a reliable reconstruction of cranial morphology and a detailed assessment of elbow and wrist anatomy. It exhibits a mosaic of primitive (stem catarrhine–like) and derived (extant hominoid–like) features that forces us to reevaluate the role played by small-bodied catarrhines in ape evolution.”
From the results: “Some cranial similarities with gibbons would support a closer phylogenetic link between the new genus and hylobatids. However, this possibility is not supported by the total evidence. A cladistic analysis based on more than 300 craniodental and postcranial features reveals that the new genus is a stem hominoid (preceding the divergence between hylobatids and hominids), although more derived than previously known small catarrhines and Proconsul.”
From the conclusion: “Our cladistic results, coupled with the chronology and location of the new genus, suggest that it represents a late-surviving offshoot of a small African stem hominoid that is more closely related to crown hominoids than Proconsul is. These results suggest that, at least in size and cranial morphology, the last common ancestor of extant hominoids might have been more gibbon-like (less great ape–like) than generally assumed.”

Figure x. Pliobates from the Miocene nests basal to all hominioids including Hylobates. Image from Alba et al. 2015.

References
Alba et al. (6 co-authors) 2015. Miocene small-bodied ape from Eurasia sheds light on hominoid evolution. Science 350:6260. online abstract
Ingicco T, de Vos J and Huffman OF 2014. The Oldest Gibbon Fossil (Hylobatidae) from Insular Southeast Asia: Evidence from Trinil, (East Java, Indonesia), Lower/Middle Pleistocene. PLoS ONE 9(6): e99531. https://doi.org/10.1371/journal.pone.0099531
Linnaeus C v 1771. Mantissa plantarum: Generum editionis VI. et specierum editionis II. L. Salvius, Holmiae. Vol. Mantissa [2] altera: Regni Animalis Appendix: 521-552.
Rocatti G and Perez SI 2019. The Evolutionary Radiation of Hominids: a Phylogenetic Comparative Study. Nature Scientific Reports 9:15267.

wiki/Ardipithecus
wiki/Hylobates
wiki/Gibbon
janegoodall.org

Mandrill and Cercocebus enter the primate branch of the LRT

No surprises here.
The African mandrill (genus: Mandrill, Figs 1, 2) and the African white-eyelid mangabey (Cercocebus, Fig 3) enter the large reptile tree (LRT, 2064 taxa, subset Fig 4) today between extinct adapids, like Notharctus, and extant rhesus monkeys, like Macada.

Figure 1. Mandrill skulls.
Figure 1. Mandrill skulls.

They say that baboons, like Mandrill
(Fig 2), are notable for retaining lemur-like claws, rather than developing nails, as in monkeys, like Cercocebus (Fig 3), and apes.

Figure 2. Mandrill skeleton.
Figure 2. Mandrill skeleton.

Mandrill sphinx
(Linneaus 1758, Figs 1, 2)) is traditionally related to the monkey Cercocebus according to genomic studies. Here extant Mandrill nests between Notharctus and Papio, the baboon, closer to lemurs than to monkeys, like Cercocebus (Fig 3).

Cercocebus torquatus
(Geoffroy Saint-Hilaire 1812, Fig 3)) is the extant collared mangabey, one of the white-eyelid Old World monkeys, here nesting between Papio and Macaca.

Figure 3. Cercocebus skull and watercolor.
Figure 3. Cercocebus skull and watercolor.

The addition of these two taxa
coincided with the reexamining of several scores related to the presence or absence of a vestigial prefrontal in related taxa. That shifted the tree topology of the LRT (subset Fig 4) moving Rocky Mountain Notharctus closer to the African apes. Lacking a basalmost taxon, the LRT now splits primates into four clades at their origin. Smilodectes is also from North America, giving rise to South American monkeys. Aegyptopithecus and Indri are African. According to the LRT primates are worldwide when we first meet them in the LRT.

Figure 4. Subset of the LRT focusing on primates.

Now we need a basalmost primate for the LRT,
one that more closely resembles outgroup taxa like the extant coatimundi, Nasua, a basalmost placental. It is interesting to note that the coatimundi is native to North America. Perhaps that is where we should look for the first radiation of primates in the Jurassic to Cretaceous. Primates eventually spread world wide during the warm Eocene, then reduced their territory to equatorial areas prior to the ascendancy of Homo sapiens.

Figure 1. The coatimundi (Nasua) compared to the ring-tailed lemur (Lemur).
Figure 5. The coatimundi (Nasua) compared to the ring-tailed lemur (Lemur).

References
Geoffroy Saint-Hilaire E 1812. Description des mammiferes qui se trouvent en
Egypte, Description de l’Egypte. II: Mammalia. L’Imprimerie Imperiale, Paris, 752 pp.
Linnaeus C 1758. Systema naturæ per regna tria naturæ, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio decima, reformata.

wiki/Baboon – Papio
wiki/Mandrill
wiki/White-eyelid_mangabey

Why a valid outgroup is so important in phylogenetic analysis

Howard et al. 2022 used genomics
(= gene analysis) to recover a cladogram of invertebrates (Fig 1). Three vertebrates and one sea squirt were included in the taxon list. Of course, these nested outside the clade of invertebrates. No outgroup was shown, unless that outgroup was something close to a sea squirt and a rotifer. That seems odd and untenable. Better to avoid wastebasket outgroups.

Figure 1. Genomic cladogram from Howard et al. 2022.
Figure 1. Genomic cladogram from Howard et al. 2022. Compare to figure 2.

The Howard et al. 2022 cladogram
(Fig 1) also lacked fossil taxa (a big problem in all genomic analyses by their very nature). The cladogram also lacked a polyclad flatworm, a taxon more primitive than any included in their cladogram. That would have made a better outgroup taxon than a sea squirt and rotifer.

Figure 2. Adding fossil taxa and two omitted worm taxa (flatworm is the outgroup) pretty much repairs the topology.
Figure 2. Adding fossil taxa and two omitted worm taxa (flatworm is the outgroup) pretty much repairs the topology.

Yet another problem:
Howard et al. cherry-picked the wrong nematodes to represent nematodes. Unfortunately parasite nematodes all require post-Cambrian taxa for their growth cycle. Omitted were free-swimming, marine, enopolid nematodes. These eat diatoms and algae that were present in Cambrian seas. Earlier we looked at the similarity of Enoplus to basal chordates and molluscs. That’s a result not predicted by the Howard et al. cladogram. Adding taxa resolves all phylogenetic problems.

Figure 3. Nematode subset of Howard et al. 2022 cladogram. Selected taxa are all parasites of post-Cambrian taxa. Omitted taxon, Enoplus, is a free-swimming marine taxa that feeds on algae present in the Cambrian.
Figure 3. Nematode subset of Howard et al. 2022 cladogram. Selected taxa are all parasites of post-Cambrian taxa. Omitted taxon, Enoplus, is a free-swimming marine taxa that feeds on algae present in the Cambrian.

I am no expert in invertebrate phylogeny,
but it didn’t take an expert to note these few omissions were ‘conspicuous by their absence’. It also didn’t take an expert to realize omitting fossils is always a mistake in deep time studies.

Perhaps due to those omssions, and others,
the results themselves suffer from rather odd pairings as sea spiders and horseshoe crabs arise from velvet worms. Centipedes are basal to krill and a blind poisonous cave crustacean is recovered basal to insects.

The usual prescription of ‘adding taxa’
adding fossils and adding a valid outgroup, are required to resolve problems in the Howard et al. cladogram (Fig 1).

References
Howard et al. (12 co-authors) 2022. The Ediacaran Origin of Ecdysozoa: Integrating Fossil and Phylogenomic Data. Journal of the Geological Society jgs2021-107. DOI: https://doi.org/10.1144/jgs2021-107