The olingo, Bassaricyon, enters the LRT amid controversy

Everyone who studies it understands
the olingo, Bassaricyon (Figs 1, 3), shares many traits with the kinkajou, Potos (Figs 2, 4). The large reptile tree (LRT, 2070 taxa) nests these two together based on traits.

Figure 1. The olingo, Bassaricyon, in vivo. This is the kind of mammal that clambered through trees during the Jurassic and Cretaceous. It’s a living fossil.

Helgen et al. 2013 report,
“Species of Bassaricyon are primarily forest-living, arboreal, nocturnal, frugivorous, and solitary,
and have one young at a time.”

Figure 2. The kinkajou, Potos, as a museum mount. Compare to the olingo in figure 1.

Bassaricyon gabbi
(Allen 1876) is the extant olingo, traditionally considered a member of the raccoon clade native to Central American rainforests.

Potos flavus
(Schreber 1774) is the extant kinkajou a tropical American relative of the North American raccoon. This fruit-eater has flat molars and a short, primate like muzzle. The tail is prehensile.

Figure 3. Olingo (Bassaricyon) skull in three views. Compare to figure 4.

Unfortunately,
molecule studies, like Koepfli et al. 2007, separate these two taxa. The Koepfli study also suffered from taxon exclusion. The authors wrote, “Cladistic analyses of morphological characters conducted during the last two decades have resulted in topologies that group ecologically and morphologically similar taxa together. Speciifically, the highly arboreal and frugivorous kinkajou (Potos) and olingos (Bassaricyon) define one clade, whereas the more terrestrial and omnivorous coatis (Nasua), raccoons (Procyon), and ringtails (Bassariscus) defne another clade, with the similar-sized Nasua and Procyon joined as sister taxa in this latter group. These relationships, however, have not been tested with molecular sequence data.”

The Koepfli team listed several genera (Fig 5) traditionally included within the family Procyonidae. Their list excludes several ingroup taxa and includes several outgroup taxa according to the LRT results.

Figure 4. Kinkajou (Potos) skull in four views.

Doubling down, the Koepfli team reported,
“Our fndings suggest that procyonid phylogenetic relationships based on morphological evidence are problematic, and further, that phylogenetic hypotheses relating fossil and living taxa based primarily on dental evidence are also open to question because of extensive homoplasy associated with this type of evidence.”

In other words, these scientists are dismissing traits they can see and measure in favor of genes that be affected by endemic viruses over deep time. They are not doubting their genomic results. The authors cherry-pick ingroup taxa, rather than including a wider gamut of fossil and living taxa and then letting the software tell them the interrelationships recovered.

Figure 5. Cladogram from Koepfli et al. 2007 cherry-picks taxa. In the LRT, the coatimundi, Nasua, is the outgroup, also basal to primates and other placentals. In the LRT Potos nests with Bassaricyon. That’s one more reason why you should avoid deep time molecular studies and use traits from a wide gamut of taxa, like the LRT.

The final phylogenetic test
is an adherence to the process of evolution: a gradual accumulation of derived traits at every node. That can only be achieved by including fossil taxa and a wider gamut of tested taxa. It is indeed unfortunate that genes too often deliver false positives. Genes hold great promise, but fail to deliver, and worse. Genes mismatch taxa and biologists fail to see that, preferring instead to embrace untenable results.

Taxon exclusion remains the number one problem
in paleontology.

Trusting deep time genomic results over trait analyses
remains the number two problem.

Figure 6. Subset of the LRT focusing on basal placentals and the clade Carnivora.

Don’t assume paradigms are true. Don’t trust genes. Don’t parrot textbooks.
Don’t borrow cladograms. Build your own cladogram. Run your own tests using traits that recover a gradual accumulation of derived traits (= maximum parsimony). When you have your own LRT, you’ll have a powerful tool you can use with authority. You will have a good grasp of the big picture and all the little details will naturally fall into place, modeling actual evolutionary events, directions, reversals and convergence.

References
Allen JA 1876. Description of a new generic type (Bassaricyon) of Procyonidae from Costa Rica. Proceedings of the Academy of Natural Sciences of Philadelphia 28: 20-23.
Helgen et al. (7 co-authors) 2013. Taxonomic revision of the olingos (Bassaricyon), with
description of a new species, the Olinguito. ZookKeys 324:1–83.
Koepfli K-P et al. (6 co-authors) 2007. Phylogeny of the Procyonidae (Mammalia: Carnivora): Molecules, morphology and the Great American Interchange. Molecular Phylogenetics and Evolution 43: 1076–1095.
von Schreber JCD 1774. Die Säugethiere vol.1 9 p.pl. 42

wiki/olingo – Bassaricyon
wiki/kinkajou – Potos