Table 1.

Upper and lower layer neuron number values in millions across 25 mammalian species. Values are averaged across individuals if more than one individual was selected per species.

Common name	Species	Upper layer neuron numbers x106	Lower layer neuron numbers x106
Paca	Agouti paca	17.45	13.8
Red panda	Ailurus fulgens	151.46	93.31
Owl monkey	Aotus trivirgatus	135.78	59.24
White-faced spider monkey	Ateles belzebuth	586.77	208.55
Marmoset	Callithrix jacchus	80.94	41.47
Pygmy marmoset	Callithrix pygmaea	66.03	30.09
Capuchin	Cebus apella	363	145.98
Fat-tailed dwarf lemur	Cheirogaleus medius	12.18	6.73
Mantled guereza	Colobus guereza	849.21	367.95
Agouti	Dasyprocta azarae	15.86	13.14
Blue-eyed black lemur	Eulemur macaco	117	62.81
Cat	Felis silvestris	88.64	54.56
River hippopotamus	Hippopotamus amphibious	348.15	201.25
Ring-tailed lemur	Lemur catta	102.05	55.68
Slender loris	Loris tardigradus	58.34	30.41
Moor Macaque	Macaca Maura	964.69	508.13
Rhesus macaque	Macaca mulatta	910.86	394.95
Hamster	Mesocricetus auratus	2.2	2.42
Wild-type mouse	Mus musculus	3.07	3.16
Sunda slow loris	Nycticebus coucang	62.39	38.91
Hamadryas baboon	Papio hamadryas	1702.44	806.24
Guinea baboon	Papio papio	2060.84	645.10
Rat	Rattus norvegicus	8.69	9.52
Red-handed tamarin	Saguinus midas	82.89	30.05
Manatee	Trichechus manatus	114.50	81.00