The Nervous Cladogram depicts a nested hierarchy of anatomical features of animal nervous systems.  All vertebrates posses the traits given at the node for the vertebrate ancestor (node 11).  All tetrapods possess the traits given at the node for the tetrapod ancestor (node 15).   All placental mammals possess the traits given at the node for the placental mammal ancestor (node 19).

     Apes consistently appear as a real, biological group—not a group of completely unrelated organisms which happen to share traits for no apparent reason.  Placental mammals are a real group.  Amniotes are a real group.  Deuterostomes are a real group, etc.  Biological groups are real—or at least there is an overwhelming amount of evidence that suggests that they are. 




1.       LUCA—Last common ancestor of all modern life on earth

--G protein coupled receptors

2.       Ancestor of Protists, Plants, Fungi, and Animals

--interactions between pheromone and G-protein coupled receptors similar to hormone-receptor interactions in animals (Blumer, 1988).

3.       Ancestor of Animals

--retinoic acid and its receptor (Schacke, 1994b). 

4.       Ancestor of Animals with Tissues

--nerve cells

--bipolar and multipolar neurons (Hickman, 138)

--some neurons are capable of secretion (Hickman)

--sensory, motor, and association neurons; motor and association neurons deep to epithelia

(Beklemishev  vol. 2, p. 75)

--interneuronal and neuromuscular synapses (Hyman, p.)

--neurosensory cells of the epithelia synapse with the nerve net. (Hickman) 

--giant fibers linking the senses to the muscles are similar to the giant fibers of many invertebrates (Fretter, p. 68).  

--ganglia can control the regular rhythms of (Fretter, 68 & 94). 

--slight centralization in some instances Beklemishev, vol. 2 p. 79-80, (Hyman)

--homolog off RXR which binds retinoic acid and then binds the DNA of crystallin genes (Kostrouch, 1998).

5.       Ancestor Bilateran Animals

--axons different from dendrites (Beklemishev  vol. 2, p. 75).

--action potentials in one direction only (can proceed in either direction in coelenterates ((Hyman, p. 377)

--cerebral ganglion (“brain”)

--longitudinal nerve chords (although not present in all Beklemishev, vol. 2, p. 80)

--brain associated with sensory structures at anterior end of animal (Beklemishev, vol. 2, p. 50-1). 

--2 main nerve chords (Rhabdocoela; Hickman)

--nerves from brain (Hickman)

--unipolar neurons (Hassler, p. 260)

—multipolar neurons, dendritic spines; soma exterior to axons, (Sarnat, 1985)

--two nerve cords homologous to equal halves of spinal cord (Sarnat, 1985)

--cells similar to hypothalamic neurosecretory cells (Sarnat, 1985)

--glia similar to astrocytes (Sarnat, 1985)

--NE, E, serotonin, Ach, neuropeptides (Sarnat, 1985)

--electrical synapses junctions (Sarnat, 1985)

--habituation (Sarnat, 1985)

--tetrodotoxin sensitive and voltage-gated fast sodium channels (Sarnat, 1985)

--dark adaptation of eye (Sarnat, 1985)


6.       A nemertine-like ancestor of complex bilateran animals

--greater cephalization and centralization (Beklemishev, vol. 2, p. 83)

--the nervous tissue migrate deeper into the body away from epithelia (Beklemishev, vol. 2, p. 83)

--greater complexity of behavior (Beklemishev, vol. 2, p. 83)

7.       Coelomate Ancestor

--peptide hormones of the vasopressin/oxytocin family (Kesteren, 1992; Youson, 1999)

--B cells and insulin (Hoar, Vol. 2)

--nuclear receptor homologous to estrogen receptors (Dehal, 2002).

--multiple families of nuclear hormone receptors (Laudet, 1992) 

8.       Deuterostome Ancestor

--dorsal nerve cord (as opposed to ventral as in many invertebrates)

--glandular region of the ventral pharynx seems to correspond to the endostyle of lancets. (Benito, form Harrison 1997, p. 72.). 

9.       Chordate Ancestor

--atria of tunicates homologous to the otic vesicles of craniates (Ahlberg, p. 62)

--tunicate larvae have gene expression in nerve chord homologous to vertebrates (such as Otr, Hox1, Hox5, Pax2/5/8 (Ahlberg, p. 21)

--while Amphioxus lacks neural crest cells, many important neural crest genes of vertebrates are expressed on the neural plate and non-neural ectoderm; the same is true of cranial placodes (Ahlberg, p.25)

-- paired nerves leaving the CNS (at least anterior end) (Willey, p. 82). 

--dorsal and ventral roots leaving nerve chord (Willey, p.83-4)

--dorsal and ventral rami  (Willey, p.85)

 --ventral roots carry muscle fibers only (Willey, p.86)

--parasympathetic innervation of gut (Romer p. 553)

 --visceral fibers which may contain sympathetic input (Willey, p. 86).

--telencephaon processing smell(Ariens)

--cerebral vesicles (Willey, p.90)

--anterior midbrain (Ahlberg, p. 15)

--medulla (Willey, p.91) 

--otoliths in tunicates (Willey, p. 10)

--in tunicates, the neural gland seems similar to the neurohypophysis . (Burighel, from Harrison, 1997, p. 270).

--tunicates; hormones similar to prolactin, beta-endorphin, and MSH. (Burighel, from Harrison, 1997, p. 279). 

--tunicate Pitx (pituitary homeobox) homolog is expressed in the neural complex (part of the embryonic pharynx) comparable to where the pituitary forms in vertebrates (Christiaen, 2002)

-- tunicates genes for all major peptide hormone receptors (such as insulin and gonadotropins), except growth hormone (Christiaen, 2002)

--the endostyle sequesters iodine and producese calcitonin,  thyroid peroxidase (which synthesizes thyroid hormones in vertebrates), and iodothyronine deiodinases (which convert thyroxine to T3) ((Burighel, from Harrison, 1997, p. 244; Christiaen, 2002; (Dehal, 2002).

       -- thyroid hormone and retinoic acid receptors  (Dehal, 2002; Christiaen, 2002).

--lancet Hatschek’s pit contains hormones similar to lutenizing hormone, chorionic gonadotropin, substance P, met-enkephalin, CCK, and gastrin (all of which are known from the hypothalamus and/or pituitary in craniates) (Stach, 2000; Gorbman, 1995)..

-- iodothyronine hormones and a protein similar to thyroglobulin in endostyle (Stach, 2000; (Ruppert, from Harrison, 1997, p. 440)

--homologs of facial glossopharyngeal and vagus (Ariens)

—trigeminal components don’t service visceral visceral structures or mucus membranes; some cutaneous innervation (Ariens)380

--trigeminal moves more caudally during development (Ariens)381

--in lancets, motor cells near spinal cavity; in jawless there are horns(Ariens)


10.   Craniate Ancestor

--medulla has choroid plexus (Hardisty, p. 312-3)

--medulla contains the nuclei of cranial nerves V through X (Hardisty, p. 312-3)

—trigeminal nerve possesses large maxillo-mandibular and ophthalmic branches (Ariens)

--jawless 2 main branches of VIII, anterior and posterior ramus (Ariens)500

--there are chromaffin cells in both jawless fish but they are located in the heart(in lampreys as well) (Hardisty, p. 359)

--a habenular complex in thalamus (Butler, 1996, p. 303

--cerebellum (Butler, p. 184)

--autonomic fibers in the vagus nerve (Romer p. 547)

--a nucleus of the superior raphe and an interpeduncular nucleus in midbrain (Butler, 1996, p.  207, 213

--autonomic innervation of the gut: ACh stimulates the gut while NE inhibits it (Hardisty, p. 360).

--dorsal and ventral roots of spinal chord join (but not in lampreys) (Romer p. 547)

-- collateral ganglia (Kardong, p. 628)

     --distinct nuclei in the tegmentum (Butler, 1996, p. 216-7

     --paired olfactory placodes form olfactory bulbs(Ariens) 1244

     --cerebral hemispheres (Ariens)1251

     --preoptic nucleus (Ariens)1247

      —septal area (Butler, 1996, p. 440

--hippocampus, corpus striatum, and part of the pallidum.  Olfactory pathways connect to the hippocampus.   (Hardisty, p. 316)

--the major regions of the cerebrum are present: the pallium (both the medial/hippocampal region and the dorsal & lateral/cortex region) and the subpallium (both the sriatum and septum) (Kardong, p. 646).

--the retina projects to the optic tectum in hagfish. (Butler, 1996, p. 244

--one semicircular canal (Romer, p. 526)

--portal system in the vicinity of hypothalamus and pituitary (Hoar, Vol. 2)

--growth hormone (Chuzhanova, 2000).

--follicles of thyroid tissue (Hoar, Vol. 2)

--B and D cells in endocrine pancreas (Youson, 1999).

--ample blood supply to endocrine pancreas (Jansson, 1998).

--cells corresponding to those of the adrenal cortex (Hoar, Vol. 2) 

--a steroid hormone receptor (Thornton, 2001).

—almost all spinal cord for local reflexes; only a few fibers from midbrain and medulla pass (Ariens)278

—all tastes but sweet (Ariens)157

--dorsal and ventral roots arise dif points; in hagfish but not lamps these unite to form a mixed nerve(Ariens)


11.   Vertebrate Ancestor

-- a single meninx (Hardisty, p. 308)

--neural crest cells (unknown if hagfish have) (Ahlberg, p. 23)

--cerebellum forms at the anterior end of fourth ventricle (Hardisty 312) as in the embryos of higher vertebrates (Hardisty, p. 327)

--cells similar to Purkinje fibers (Hardisty, p. 312)

--midbrain contains the nuclei of cranial nerves III and IV (which departs the brain dorsally) (Hardisty, p. 311)

-- large reticular cells, nucleus interpeduncularis, part of tectum ependymal, optic tract to tectum, lateral geniculate nucleus, dorsal and ventral thalamus, neural hypophysis, pars intermedius, lateral hypothalamus (Ariens)1192

--the diencephalon can be divided into a thalamus, hypothalamus, and epithalamus and it contains a pineal body and a habencular nucleus (Hardisty, p. 310)

--the region which unites the diencephalon to the midbrain also contains a pretectum and a posterior tuberculum. (Butler, 1996, p. 259

--an outer layer of large cells, which may be the precursors to the Purkinje cells of gnathostomes, and an inner layer of small cells(Ariens)707

--cerebellar connections which are present in gnathostomes including bulbocerebellar, crossed and uncrossed tectocerebellar, cerebellotectal, cerebellotoral, and bello-tegmental connections and the tractus lobo-cerebellaris (Ariens) 708

the vestibular nerve projects to cerebellum (Ariens)708

     --a torus semicirularis (inferior colliculus in mammals). (Butler, 1996, p. 229 

     -- medial, dorsal, and lateral subdivisions of the pallium (Butler, 1996, p. 263

     --an epiphysis and a pineal which projects to the pretectum. (Butler, 1996, p. 302

      --visual input into the pretectum. (Butler, 1996, p. 281

--olfactory bulbs

--bipolar neurons connect the olfactory bulbs to the olfactory epithelia and the olfactory pathway is structured similarly to that of higher vertebrates (Hardisty, p. 316)

the geniculate primordium of the thalamus receives visual input (Hardisty, p. 319)

--the hypothalamus contains the preoptic nucleus, mammillary body, and neurons capable of secretion. (Hardisty, p. 320-1)

--tectum processes visual information (Hardisty p. 326)

--glial cells (Hardisty, p. 335)

 --the spinal cord contains spinocerebellar and tectospinal tracts ((Hardisty, p. 328)

--GABA is an inhibitory neurotransmitter while glutamate is excitory (Hardisty, p. 328)

--in the spinal chord, the dorsal root is more restricted to sensory information and there are dorsal root ganglia (Hardisty, p. 357)

--oculomotor and trochlear nerves which control eye muscles (hagfish lack these but their eyes are degenerate) (Hardisty 355-7).

--ANS more developed in lampreys (Hardisty, p. 359)

-- the heart is innervated by the vagus (although ACh and vagal stimulation stimulate the heart, unlike the situation in higerh vertebrates (Hardisty, p. 358).

--the hypothalamus integrates visceral input (Romer p. 586).

--anterior commissure connects cerebral hemispheres (Romer, p. 594)

—trochlear emerge dorsally (Ariens)517

--nuc for accessory nerve (Ariens)587

-- nucleus magnocellus inferior (Ariens)522

--striatal regions (Ariens)1247

--medial olfactory nucleus (Ariens)1247

--lobus subhippocampus (Ariens)1247

--enteric ANS plexuses (Kardong, p. 628).

--two semicircular canals (Romer, p. 526)

--rods in eye (Kardong, p. 665)

--3 semicirular canals (Kardong, p. 682)

--corpus striatum

--distinction of pars distalis and pars intermedius of the pituitary  (Hoar, Vol. 2)

--thyroid follicles are concentrated in ventral pharynx and have ample blood supply (Hoar, Vol. 2)

-- iodine is concentrated in the colloid around thyroid follicular cells (Hoar, Vol. 2)

--F in endocrine pancreas (Youson, 1999).

--innervation of endocrine pancreas (Jansson, 1998).

--chromaffin-like cells are present in the hearts of lampreys and higher vertebrates including mammals. (Webster, 1974, p. 127). 

--multiple steroid hormone receptors, including those for estrogen and progesterone (Thornton, 2001).

--The traits which seem to be present in conodonts and gnathostomes which are absent in lampreys and hagfish include an olfactory tract, larger cerebellum, pretrematic branches of branchial nerves, flattened spinal cord, and a vertical semicircular canal (Donoghue, 2000).


12.   Gnathostome Ancestor

--distinct gray and white matter in spinal cord; horns of spinal cord (which are not present in lampreys, Hardisty p.313—check sharks)

--ANS input to blood vessels(Romer p.554) and

--autonomic ganglia along the spinal cord (Romer p.554) 

—trochlear fibers no longer cross cerebellum and nulceus no longer within cerebellum (Ariens)710

—cerebellum composed of an unpaired corpus and 2 lateral auricles. (Ariens) 

--the corpus cerebellum contains a pars anterior and pars posterior. (Ariens)

—molecular, Purkinje, and granular layers (Ariens)720

 —dorsal and ventral spinocerebellar tracts, although they are largely uncrossed (Ariens)722

--no ependymal part midbrain(Ariens)

--tectum better developed (Ariens)1192

--increase in basal region of midbrain (Ariens)1192

cerebellar tracts to diencephalon (Ariens)1192

--connections of vestibulocochlear nerve to hypothalamus (Ariens)1192

--midbrain affects body position through connections with cerebellum and medulla (Ariens)1193

--velum transversum in diencephalon (Ariens)1193

--increased development of lateral geniculate nucleus (Ariens)1193

--connections between ventral thalamus and hypothalamus to telencephalon (Ariens)1193

--tractus pallii (Ariens)

--olfactory  fibers no longer project to all pallial areas (Butler, 1994b).

--ganglion sacci vasculosi in hypothalamus (Ariens)1194

--a locus coeruleus in midbrain (Butler, 1996, p. 207)

--cuneiform, intercollicular,  red nuclei and a substantia nigra in (Butler, 1996, p. 216-7

--in the ventral thalamus, gnathostomes possess a nucleus intermedius, ventromedialis, and ventrolateralis.  (Butler, 1996, p. 262). 

--the pineal projects to the habenular nuclei (Butler, 1996, p. 301-2

—the hypothalamus can be divided into a medial region around third ventricle and 2 inferior lobes (Butler, 1996, p. 332

—mesencephalic nucleus for trigeminal (Ariens)

--sensory components of facial and vagus (branchiomeric nerves) decrease (Ariens)

—facial nucleus more caudal; trigeminal supplies head (Ariens)

—separation of roots of abducens and trigeminal 518

—vagal nucleus shifts caudally, separates from glossopharyngeal (Ariens)523

--trochlear nucleus moved cranially (Ariens)526

—facial nucleus shifts cranially (Ariens)531

—nuceli of cranial nerves III and IV close proximity (Ariens)533

—fasciculus solitarius (Ariens)

--increase in interconnections between regions of telencephalon (Ariens)1262

--tractus olfacto-habenularis anterior and posterior (Ariens)1264

--connections between the dorsal thalamus and striatum (Ariens)1266

-- the area periventricularis ventrolateralis and nucleus superficialis basalis may be equivalent to the dorsal and ventral striatal regions in mammals.  (Butler, 1996, p. 272

—medial and lateral septal nuclei (Butler, 1996, p. 440

—dorsal and medial pallium receive visual info (Butler, 1996, p. 370

—striatum and pallidum distinct regions of basal ganglia (Medina, 1995). 

--basal ganglia and some of its connections (Medina, 1995). 

--increased the non-olfactory regions of the cerebrum (Romer p. 588)

--pyramidal cells (in hippocampus at first) (Hassler, p. 117)

--bed nucleus of anteriorhippocampal commissure (Hassler, p. 121)

--smooth muscle in iris (Romer, p. 508)

--lens attached (Romer, p. 509)

--primitive eyelids (Romer, p. 516)

--saccule and utricle in the inner ear (Romer, p. 526)

--duplication of GnRH gene (Lovejoy, 1992)

--portal system between hypothalamus and pituitary (Hoar, Vol. 2)186-7

  -- pars nervosa is defined (Hoar, Vol. 2)186-7  

-- growth hormone has both growth and diabetogenic effects (Hoar, Vol. 2)

-- POMC gene (Alrubaian, 2003). 

--the ultimobranchial body (Hoar, Vol. 2;(Shinohara-Ohtani, 1998). 

--  endocrine pancreatic islets located in compact exocrine tissue (Hoar, Vol. 2)

--A in endocrine pancreas (Youson, 1999).

--adrenal glands composed of adrenocortico tissue (Hoar, Vol. 2) 

--androgen receptors (Thornton, 2001).

--round spinal instead of more primitive flat (jawless)(Ariens)

--dorsal and ventral can still leave sep

dorsal and ventral horns (Ariens)160

no medial lamniscus; nuc gracil and cunaeatus (Ariens)163

--tract homologous to spinotectal tract (Ariens)164

--dorsal spinocerebellar tract (Ariens)166

- myelinization (Ariens)278

-- spino-bulbar tract (Ariens)279

-- spinocereb; reticulo-spin (Ariens)279



13.   Bony Fish Ancestor

 --autonomic gray rami and sympathetic chains (Romer p.554)

--the ophthalmicus profundus is always part of the trigeminal (Romer p. 560).

--chromaffin cells separate from ganglia (Kardong, p. 628)

--a region homologous to the ponto-bulbar body and tractus mesencephalo-cerebellaris and all fibers are crossed in the olivo-cerebellar tract (Ariens)728-36

--cerebellar ventricle is reduced (Ariens)729

--a number of commissures in the midbrain (Ariens)1195

--development of tori semicirculares (Ariens)1195

--connections of the hypothalamus to regions which regulate autonomic function (Ariens)1195

—sulcus limitans dividing dorsal sensory and ventral motor less obvious (Ariens)338

--the red nucleus forms part of a rubrospinal tract. (Butler, 1996, p. 216-7

      --a nucleus isthmi in midbrain (Butler, 1996, p. 207)

—suprachiasmatic nucleus, preoptic nuclei, and dorsal and ventral hypothalamic nuclei around third ventricle (Butler, 1996, p. 333

--a nucleus isthmi which projects to and from the optic tectum (the mammalian nucleus parabigeminalis is considered its homolog) (Wiggers, 1991).

--since bony fish, there has been at lease one basal optic nucleus in the tegmentum.  (Butler, 1996, p. 290

—basal ganglia have 2 major groups of projection neurons which release substance P and enkalphins (Medina, 1995). 

--lens attaches to ciliary body (Romer, p. 510)

--collateral ganglia (9)

-- two conserved forms of TRH (Harder, 2001).

--neurohypophysis and adenohypohysis contact each other (Gorbman, 1995)..

--prolactin performs a variety of functions, including parental behavior and even examples of producing nourishment for young (Hoar, Vol. 2)219-20). 

-- N-acetylation of a-MSH and b-endorphin occurs before they are secreted (Dores, 1994). 

--TSH (Hoar, Vol. 2)

--all major groups of steroid hormone receptors found in mammals (Thornton, 2001).

cervico-brachial plexus (Ariens)

--dorsal and ventral roots always fused, although dorsal and ventral may not arise at exactly same level (although closer than in lower) (Ariens)

--since fish, collateral branches of motor neurons, morecommon in mams (Ariens)171

chain ganglia; rami communicates connect some chain ganglia

splanchnic collateral ganglion near head (Ariens)172

--myelinated white rami of preganglionic fibers to ganglion (Ariens)

--ventrospinocerebellar tract (Ariens)178

--reticulospinal tract (Ariens)179

--bony—motor neuron soma more ventral (Ariens)280

--bony vestibulospinal

--spinothalam tracts homol to spino-mesencephalic and spinobulbar tracts of lower



14.   Sarcopterygian Fish Ancestor

--hippocampus along medial and dorsomedial wall of evaginated cerebral hemisphere (Hassler, p. 117)

--fornix connects hippocampus and septal region (Hassler, p. 122)

--olfactory tubercle with same subdivisions as observed in mammals (Hassler, p. 122)

--paleostriatal and nestriatal areas (Hassler, p. 127)

--lagena from vestibule detects sound (9)

--ANS fibers travel only through ventral roots (9)

--similarities in neurohypophysial hormone sequences (Shinohara-Ohtani, 1998). 

--POMC gene  contains g-MSH sequence (Lee, 1999).

--structural changes of ultimobranchial body (Shinohara-Ohtani, 1998)

15.   Tetrapod Ancestor

--inferior colliculus (Romer p. 585)

--reticular regions in midbrain found in higher vertebrates (Ariens)1196

--optic tectum covers tori semicirculares (Ariens)1196

afferent fibers lead to optic tectum, even in blind amphibians (Ariens)1196

--dorsal thalamus increased (Ariens)1197

--connections between the dorsal thalamus and telencephalon (Ariens)1197

--olfactory pathways connecting the diencephalons to the telencephalon, such as the stria terminalis (Ariens)1197

--the nucleus ventrolateralis is divided into a dorsal and ventral regions. (Butler, 1996, p. 262

-- a lateral hypothalamic nucleus. (Butler, 1996, p. 336

--increased the non-olfactory regions of the cerebrum (Romer p. 588)

--a single deep cerebellar nucleus (Butler, 1996, p. 194)

-- a nucleus accumbens and an entopeduncular nucleus. (Butler, 1996, p. 272

—posterior ramus of cranial nerve VIII carries information from cochlea (Ariens)

--amphibs cerv and lumbar enlargements(Ariens)

Giant ROhon Beard present in development but not in adult(Ariens)

--Pacinian corpuscles (Ariens)186

--increase volume dorsal column (Ariens)188

--accessory olfactory bulb (Ariens)1293

--amygdaloid complex (Ariens)1298

caudate nucleus (Ariens)1298

--nucleus accumbens (Ariens)1298

--VNO and nerves (Ariens)1300

--connections of stria medullaris found in higher vertebrates (Ariens)1306

--tractus amygdalo-habenularis (Ariens)1307

--median forebrain bundle (Ariens)1307

--fornix (Ariens)1307

--bed nucleus of anterior commissure (Ariens)1308

--striohypothalamic tract (Ariens)1310

--primordium pallii dorsalis (Ariens)1311

--non-olfactory processes in pallium (Ariens)1311

—thalamus, pretectum, hypo, medial pallium (Butler, 1995).

--first touch receptors in which dendrites form part of a corpuscle (Romer, p. 497)

--first proprioceptors (Romer, p. 498)

--vomeronasal organ (Romer, p.504)

--movable eyelids (Romer, p. 517)

--lacrimal canals in eye (Romer, p. 517)

--hair cells involved in hearing (Romer, p. 532)

--auditory ossicle involved in hearing (the stapes) (Romer, p.532)

--papilla basilaris may be primitive organ of Corti in amniotes (Kardong, p. 684)

--parathyroid glands (Weichert, 1970)246-7


16.   Amniote Ancestor

--both the cerebrum and tectum (as opposed to the tectum alone)are important association (Romer p. 585)

--loss of giant fibers which exist in invertebrates, Amphioxus, fish, salamanders, and frog tadpoles (Willey, p. 94)

-- two deep cerebellar nuclei (Butler, 1996, p. 194

--a fissure prima, posterior fissure, and a pars lateralis (may be homologous to cerebellar hemispheres) (Ariens)750-2.

--homolog of the large-celled region of nucleus ruber (Ariens)1197

--nucleus entopeduncularis in ventral thalamus (Ariens)1199

-- pedunculopontine nucleus. (Butler, 1996, p. 216-7

--most amniotes have similar organization of hypothalamus ahich includes anterior nucleus, preoptic area (medial and lateral), supraoptic nucleus, suprachiasmatic nucleus, paraventricular nucleus, mamillary bodies (medial and lateral nuclei), posterior nucleus, lateral hypothalamic area, tuber cinereum, dorsomedial nucleus, and ventromedial nucleus.

(Butler, 1996, p. 336

--the medulla includes a superior olive nucleus (although there are the beginnings of this nucleus in amphibians), a true lateral lemniscus tract, superior vestibular nucleus of Beccari (nucleus of Bechterew in mammals), a nucleus angularis (homolog of mammalian dorsal cochlear nucleus), a more lateral position of visceral efferent nuclei, ventrolateral visceral nuclei, and nuclear masses and tracts of cochlear system similar to mammals.  (Ariens)466-560

--There are no longer any lateral line organs or nerves (which are present in some aquatic amphibians)


--increase in size of telencephalon (Ariens)1313

--greater separation of olfactory bulbs (Ariens)1314

--caudate nucleus (Ariens)1319

--lentiform nucleus (Ariens)1319

--dorsal ventricular ridge (Ariens)1319

--putamen (Ariens)1321

--claustrum (Ariens)1321

--nucleus epibasalis (Ariens)1321

--nucleus centralis (Ariens)1321

--nucleus basalis accumbens (Ariens)1321

--bed nucleus of the stria terminalis (Ariens)1322

--globus pallidus (Ariens)1323

--piriform lobe cortex (Ariens)1336

--medial and lateral septal nuclei (Ariens)1408

--dorsal pallium two divisions: medial lemnopallial division and a lateral collopallial division (Butler, 1996, p. 377

—medial division of dorsal pallium and lateral division of dorsal pallium, ventricular and subventricular divisions of the lateral division of dorsal pallium, no overlap between lemnothalamic and collothalamic projections to the dorsal pallium, lemnothalamic fibers project through lateral forebrain bundle to dorsal pallium and striatum, at leaset some lemnothalamic tracts are bilateral, the lateral part of the medial division of the dorsal pallium alone receives visual projections from the lemnothalamus, the medial part of the medial division of the dorsal pallium alone receives somatosensory and limbic input from lemnothalamus, the lemnothalamus projects to both divisions of the dorsal pallium, dorsal pallium projections to dorsal thalamus, dopaminergic fibers to dorsal pallium, GABA-containing neurons in both divisions of dorsal pallium, projections of dorsal pallium to striatum (Butler, 1994)

--Division of amygdale in to several regions (Butler, 1996, p. 455

--Limbic system increase and differentiates  (Butler, 1996, p. 456

--Lemnothalamic and collothalamic visual pathways (Butler, 1996, p. 391

--a ventral lateral geniculate nucleus. (Butler, 1996, p. 262

--a thalamic reticular nucleus. (Butler, 1996, p. 263

--hypothalamus is involved in temperature (Romer p. 586).

--increased importance of thalamus as sensory relay center for cerebrum (Romer p. 586-7)

--posterior column—medial lemniscus pathway (Hassler, p.319)

--nucleus gracilis and nucleus cuneatus in medulla (Hassler, p.319)

--spinal nerves are incorporated into the brain, forming cranial nerves XI and XII (Kardong, p. 618).

—dorsal thalamus more developed (Butler, 1995).

--central posterior nucleus and medial geniculate nucleus project to striatum (Butler, 1995).

--visual pathways from midbrain project to both striatum and pallium (Butler, 1995).

--ipsilateral sensory porjections from midbrain to pallium (Butler, 1995).

--main abducens nucleus moves to level of facial  reps(Ariens) 623

--hypoglossal nucleus shifts forward (Ariens)556

--longer hypoglossal fibers through medulla (Ariens)557

--the ventral tegmental area and substantia nigra project to the striatum with dopaminergic neurons (Medina, 1995). 

—dorsal thalamus projects to telencephalon (Pritz, 1995)

--projection of thalamic reticular nucleus to dorsal thalamus (Pritz, 1995)

—reciprocal circuits between dorsal thalamus and cerebrum (Pritz, 1995)

—lemnothalamic medial pallial division and collothalamic lateral pallial division  (Butler, 1994b)

--regions of pallium which form the extrastriate, auditory, secondary somatosensory, and other corticies in mammals (Butler, 1994b)

--a number of shared pathways such as homologs of mammalian wuditory pathway from inferrio colliculus to medial geniculate body to suditory cortex, from the retina to the dorsal lateral geniculate nucleus to the striate cortex, (Butler, 1994b)

--homologs of ventral nuclear group, posterior nuclear group, (Butler, 1994b)

--no alternate of dorsal and ventral roots (some in amphib larvae)

--substantia gelatinosa over dorsal horn (Ariens)198

--reptiles have nucleus cuneatus and gracilis (Ariens)200

--reps have fascic gracil and cuneatus although some organization in apmphibs (Ariens)

medial lemniscus (Ariens)

--taste buds no longer on skin (Romer, p.498)

--olfactory epithelium on superior part of nasal cavity (Romer, p.503)

--lens flexible, allowing accomodation (Romer, p.510)

--lateral line system lost (Romer, p. 518)

---cartilage surrounding external auditory meatus (Romer, p.531)

--organ of Corti in ear (Kardong, p. 684)

17.   Mammal Ancestor

--the tectum is reduced as the cerebrum is the main association center (Romer p. 585)

--the tectum becomes less important in visual processing and many visual fibers proceed to the thalamus (Romer p. 585).

-- three deep cerebellar nuclei: the medial (fastigial) nucleus, lateral (dentate) nucleus, and the nucleus emboliformis.  (Butler, 1996, p. 194

--increase in floccular region of cerebellum (Ariens)775

--both floccular and parafloccular regions of cerebellum(Ariens)775

--anterior, middle, and posterior lobes of cerebellum (Ariens)775

--fissura postpyramidalis, prepyramidalis, uvulo-nodularis of cerebellum(Ariens)775

--mammals 3 cerebellar peduncles (Ariens)798

—cortico-ponto-cerebellar tracts (Ariens)798

--optic tectum forms superior colliculi (Ariens)1202

--tori semicirculares form inferior colliculi (Ariens)1202

--increased connections between superior colliculus and diencephalon (Ariens)1202

--incrase in the medial longitudinal fasciculus (Ariens)1202

--red nucleus more prominent (Ariens)1202

--development of the pedunculo-tegmental system (Ariens)1202

--increased development of the dorsal thalamus (Ariens)1203

--medial geniculate nucleus of thalamus relays auditory information to auditory cortex (Ariens)1204

--lateral geniculate nucleus of thalamus relays visual information to visual cortex (Ariens)1204

--lateral thalamus relays information to cerebral cortex (Ariens)1204

—increase size of trigeminal (Ariens)401

—more occulomotor fibers cross to the opposite side of the brain (Ariens)565

—hypoglossal nucleus independent of gray matter spinal cord (Ariens)578

glossopharyngeal  nucleus forms part of nucleus ambiguous (Ariens)622

--the pretectum is more highly differentiated. (Butler, 1996, p. 288

--3 accessory optic nuclei.  (Butler, 1996, p. 292

-- the accessory optic nucleus is connected to the oculomotor complex rather than the cerebellum. (Butler, 1996, p. 292

--anterior and posterior paraventricular nuclei, medial and lateral habenular nuclei. (Butler, 1996, p. 304

--lemnothalamic nuclei move caudally. (Butler, 1996, p. 313

--a dorsal lateral geniculate nucleus, ventral nuclear group, anterior nuclear group, medial nuclear group, intralaminar nuclear group, lateral posterior-pulvinar complex, medial geniculate body, limitans/suprageniculate complex, and lateral part of posterior nuclear group.  Many nuclei exist in non-mammals, especially birds and reptiles, and many are comparable to these. (Butler, 1996, p. 318

--part of the lateral lemniscus proceeds to the medial geniculate nucleus of thalamus and from there to the auditory cortex.(Ariens)502

 --external cuneate nucleus (Ariens)485

--nucelus medialis (Ariens)488

--nucleus of von Monkow (Ariens)486

-- nucleus of Bechterew doesn’t extend as far caudally(Ariens)

--the amygdala is more highly developed. (Butler, 1996, p. 264

--an olfactory cortex which contains anterior olfactory nucleus, prifiform complex, an olfactory tubercle, a cortical amygdale, and an entorhinal cortex. (Butler, 1996, p. 268)

--the septum contains lateral septal nucleus, medial septal nucleus, the nucleus of the diagonal band of Broca, septofimbrial nucleus, and a triangular nucleus. (Butler, 1996, p. 278

—increase the percentage of ipsilateral optic fibers which do not cross to the opposite side of the brain at the optic chiasm. (Butler, 1996, p. 381

striate (named for a band in layer IV of cortex) and extrastriate regions of visual cortex (Butler, 1996, p. 385

—motor cortex plus area of combined motor and sensory cortex 399

--connections between pineal and habenular nuclei are reduced in mammals. (Butler, 1996, p. 301-2

--the facial nerve expands its area of innervation (Romer p. 560).

--hypothalamus has roles in heartbeat, respiration, blood pressure, and sleep (Romer p. 586).

--fornix (Romer, p. 590)

--corticospinal tract (Hassler, p. 321)

--at least 20 isocortex areas, including the primary visual cortex, the primary somatosensory cortex, (Kaas, 1995).

—V1 projects to V2 and from there to several regions medial and lateral to V2(Kaas, 1995).

—M1 motor area of cerebral cortex (Kaas, 1995).

—contralateral representaiton on sensory and motor maps (Lende, 1964)

--olfactory region of cerebrum inferior to rhinal fissure (Romer 592)

--specialized muscle fibers in spindles for proprioception (Romer, p. 498)

--taste buds concentrated on tongue (as opposed to pharynx; reptiles and birds have few taste buds on tongue) (Romer, p.498)

--most modern mammals are not responsive to color, suggesting the first mammals adapted to nocturnal life (Romer, p. 514)

--not all optic fibers cross at chiasm (Romer, p. 516)

--space for inner ear expands into the mastoid bone (Romer, p.530)

--pinna of external ear (Romer, p. 531)

—lemnothalamus moredeveloped (Butler, 1995).

Inputs to rostral dorsal thalamus (Butler, 1995).

—all dorsal thalamic nuclei participate in  local  pathways and relays to the cerebrum (Pritz, 1995)

—expansion of the principal nucleus of the inferior olivary complex (Johnson, 1982)

--spinal doesn’t extend the length of vert since mono (Ariens)221

(Ariens)221—human embryos begin with coccygeal ganglia which degenerate; a coccygeal medullary vestige is retained later in fetal 221

--increase in dorsal column 259

--placent incrase size nuc cuneatus and gracil 263

--red nucleus increase in size; rubrospinal tract (also known in birds) large (Ariens)270

cortico-spinal only in mammals; in mono and marsupials it only reaches the cervical region of the cord; in insectivores and bats, the few cortico-spinal also end in cervical region (Ariens)271

--mamms dorsal horns divied into zona marginalis, substanctia gelatinosa of Rolando, main mass

--mams, some proprioceptive collaterals to dorsal column & from there nuc gracil and cuneatus; more in higher mammals (Ariens)288

Ventral vagal comples—mammals, may have role in social behaviors (Porges, 1988)

--parathyroid glands develop from the dorsal portions of pharyngeal arches.  (Weichert, 1970)246-7


18.   Therian Mammal Ancestor (Marsupials and Placentals)

--cerebellar hemispheres increase in size (Ariens)775

—presylvian sulcus (Ariens)1531

Cortex made of 6 layers—at least marsups (Ariens)1568

--lagena coiled to form cochlea (Romer, p.535)

--lagenar macula lost in ear (Romer, p.532)

—S2—secondary somatosensory area(Kaas, 1995).

Most therians have some degree of separateion between claustrum and cortex; in primates they are completely separated (Johnson, 1994).

—separation of external cuneate nucleus from the cuneate-gracile nuclear complex (Johnson, 1994).

Modification of dorsal cochlear nucleus to an outer molecular layer, a layer of granule and fusiform cells, and a core of mixed cell types in therians (Johnson, 1994).

—SII (Lende, 1964)

--somatic sensory area in middle of brain (Lende, 1964)

—a distinct monolayer of mitral cells in olfactory bulb (Johnson, 1982)

—optic tract fibers to the anterior colliculus project to a deep rather than a superficial layer (Johnson, 1982)

—cingulate and subcortical cortices, dorsal column nuclei, trigem nuc, parabrachial nuc, cerebellum, striattum, olfact cortex (Butler, 1995).

loss of contralateral lemnothalamic projections (Butler, 1994b)

-- increase in projections to dorsal thalamus (Butler, 1994b)

--vertical tympanic membrane (4)


19.   Placental Mammal Ancestor

--end of midbrain exposure (Romer p. 592)

--gyri and sulci increase surface area of cerebrum in most placentals (Romer, p. 593)

--6 cellular layers in the neopallium (Romer, p. 594)

--corpus callosum (Romer, p. 594)

--placental mammals multiple nuclei of the anterior, medial, and intralaminar groups and a lateral posterior-pulvinar complex, unlike monotremes. (Butler, 1996, p. 320

—increase in number of small and medium sized cells in and around trigeminal nucleus (Ariens)610

--reduction in forward extension of efferent facial nucleus(Ariens)599

—ventrolateral position of nucleus magnocellularis (Ariens)495

—tuberculum acusticum and ventral cochlear nucleus enlarged (Ariens)496

—hippocampus moves laterally (Ariens)1479

—sulcus intercalates, rostralis, occipito-temporalis, suprasylvian (Ariens)1522, 1543

—interparietal (Simian) sulcus (Ariens)1550

—coronal sulcus and ansate sulcus (form central sulcus in primates) (Ariens)1535

Above insectivores—claustrum better differnetiated from surrounding areas (Kowianski, 1999)

--M2 primary and secondary motor fields (Kaas, 1995).

--hippocampus shifts posteriorly (Hassler, p. 119)

—facial cranial nerve passes ventral to trigeminal nuclear complex (Johnson, 1982)

—no oil droplets in retinal cones (Johnson, 1982)

—medial position of principal nucleus of the inferior olivary complex (Johnson, 1982)

--increase in digital dexterity

--fibers of dorsal lateral olfactory tract pass through accessory olfactory formation (also in rodents)

--corpus callosum connects cerebral hemispheres

--no oil droplets in retinal cone receptors

--most placentals, lateral cortico-spinal tract no longer in dorsal column (as in mon, marsup, ungulates and rodents) (Ariens)291


20.   Primate Ancestor

--nucleus intercalates divides into nucleus emboliformis and nucleus globosus (Ariens)794

-- increase lamellation of cerebellum (Ariens)794

--extension of red nucleus into the diencephalon (Ariens)1202

--increased size of neocortex (and also at following nodes) (Ankel-Simons, p. 175)

--increased visual areas (Ankel-Simons, p. 175)

--central sulcus (in other placental groups this sulcus may or may not be present) (Romer, p. 595)

--sylvian fissure in cerebrum (Ankel-Simons, p. 187)

--cerebral hemisphere extends over part of olfactory bulb (Ankel-Simons, p. 187)

--fovea in eye (Ankel-Simons, p.376)

--septum velum narrows (Hassler, p. 398)

—hypoglossal nucleus subdivided (Ariens)583

--ramus descendens hypoglossi from spinal cord rather than hypoglossal nucleus (Ariens)583

--prominent calcarine sulcus in primates (Butler, 1996, p. 386

--tuberculum olfactorium(Ariens)1407

--dentate gyrus (Ariens)1413

--internal capsule of projection fibers to the cortex (Ariens)1458

--fronto-pontine, occipito-pontine, and temporo-pontine tracts (Ariens)1463

--corticospinal, corticobulbar,a nd corticorubral tracts (Ariens)1464

some marsups have a dorsal corpus callosum (Ariens)1466

--association tracts (although many have homologs in reptiles) (Ariens)1471

--fissure hippocampus (Ariens)1517

fisura rhinalis (Ariens)1517

-- paracalcarine sulcus (Ariens)1523

—sulcus temporalis superior (Ariens)1548

--gyrus retrosplenius, sulcus temporalis inferior, sulcus postlateralis (lunatus), sulcus interparietalis (latealis) (Ariens)1666

Primates increase in extension of corticospinal tract in spinal cord (Heffner, 1983)

Priamtes more ventral spinal cord gray receiving corticospinal terminals (Heffner, 1983)

Digital dexterity and the size of the corticospinal tract increase gradually throughout the primates (Heffner, 1983)

The thalamic pulvinar nucleus increased in size (Armstrong, 1981)..

--increase in corticospinal in primates (Ariens)274

(Ariens)223 in primates, increase size cervical enlargement spinal

Primates—about half ipsilateral (Johnson, 1994).

—multiple sensory representaiton arease for each sense (Kass, 2000)

—3 auditory fields with primary-like characteristics that receive input from the thalamus and have a developed granule layer 4 (Kass, 2000)

--a corticospinal projection from the mouth field of the agranular cortex (Fogassi, 1994).

--changes in tectal connections to retinas (Dermoptera) (1)

--highly developed sight (2)

--general increase in brain size: body size (2)

--changes in the corticospinal tract in the ventralmost lamina receiving synapses and the lamina receiving densest synapses (2)

--large pulvinar nucleus (2)

--equivalent tectopetal connections to the anterior colliculus of one side from both retinas (2)

--duplications of growth hormone gene (Chuzhanova, 2000)

--increase in the size of brain regions processing vision contributed to the increase in encephalization (Kirk, 2006).

-- increase the density of Meissner corpuscles (Dominy, 2004).

--The degree of orbital convergence increased in primates (Dominy, 2004).


21.   Anthropoid Primate Ancestor (monkeys, apes, and humans)

--(and tarsiers) 4 cell layers in thalamic geniculate body  (Ankel-Simons, p. 182)

--orientation of lateral geniculate nucleus ventral and rotated (Ankel-Simons, p. 188)

--septum pellucidum (Hassler, p. 398)

--(and tarsiers) olfactory area reduced (Ankel-Simons, p.189)

--greater development of gyri (Ankel-Simons, p. 190)

--stereoscopic vision (Ankel-Simons, p. 190)

--enhanced sense of touch (Ankel-Simons, p. 190)

--greater specialization of lateral geniculate nucleus (Ankel-Simons, p.190)

--large integration areas develop in all 4 lobes of brain (Ankel-Simons, p. 191)

--monkeys increase size of trigeminal  nucleus(Ariens)401

--(and tarsiers) rhinarium lost (Ankel-Simons, p. 350)

--(and tarsiers) upper lips lose some of their attachments and more free to move (Ankel-Simons, p.350)

--(and tarsiers) no tapetum lucidum (Ankel-Simons, p. 375)

--cones outnumber rods (Ankel-Simons, p. 377)

Somatosemsory cortex 1 has a complete mirror image in anthropoids (monkeys and apes). (Johnson, 1994).

--Loss of accessory olfactory bulb in OW and apes, also in some bats (Johnson, 1994)..

--mirroring of sensory body map in isocortex

--neocortex no longer smooth; contains gyri and sulci (unlike some insectivores and prosimians) 

--large association areas within frontal, parietal, temporal, and occipital lobes

--optic areas highly developed, olfactory areas reduced

--retina has both rods and cones; cones outnumber rods

--fovea and macula densa

--increase in the size of brain regions processing vision contributed to the increase in encephalization (Kirk, 2006).

--The degree of orbital convergence increased in primates and in higher primates. Anthropoids evolved a retinal fovea, evolved larger optic nerves, more orbital convergence, and decreased the size of the cornea (Dominy, 2004).


22.   Catarrhine Primate Ancestor (Old World Monkeys, apes and humans)

--vomeronasal organ much reduced in adults (Ankel-Simons, p. 354)

--ability to taste the protein thaumatin (from African berries) as sweet; other primates don’t taste  (Ankel-Simons, p. 359)

--long, bony auditory meatus (Ankel-Simons, p. 369)

--accessory olfactory bulb reduced or absent (Hassler, p.387)

23.   Ape Ancestor

--facial rootlets more caudal apes (Ariens)606

—loss of the “knee” of the inferior facial root fibers path (Ariens)606

—sulcus intercalates and genualis form cinguli (Ariens)1526

-- anterior and posterior calcarine sulci fuse and divide into 2 caudal branches (Ariens)1527

—gyrus transverses connects supertemporal convolution and gyrus longus anterior (Ariens)1547

—increase development of posterior parietal lobe(Ariens)

--Loss of the external granular layer of the dorsal cochlear nucleus in embryonic development in apes (Johnson, 1994).

--While the lateral posterior nuclei of the thalamus have kept the same number of neurons in humans as in apes, the human pulvinar nucleus has twice the number of neurons (Armstrong, 1981).

--The thalamic pulvinar nucleus increased in size in primates and is the largest thalamic nucleus in apes (Armstrong, 1981)..

--ability to recognize mirror reflection of self (5)

--language ability (sign or spoken) (5)

--cerebral asymmetries that exist in apes (larger one given): left sylvian fissure,  left occipital lobe, left lateral ventricle (5)

-- Higher ape—sulcus frontalis inferior (Ariens)1539

--Higher apes—gyrus postcentralis is separate from parietal lobe (Ariens)1553

--Higher apes—increase in volume of limbic nuclei (Armstrong, 1980a)

--Cerebral asymetries are known in fossil hominids and apes including a longer left sylvian fissure.  Those of higher apes and fossil hominids are similar to those found in humans (LeMay).

--The ACC of non-apes lack clusters of spindle cell pyramidal neurons.  Orangutans possess some clusters (Uddin, 2004).



24.   African Ape Ancestor

Af ape—sulcus principalis/frontal-marginal fissue (Ariens)1538

Af—median nerve ussually innervates 3 ½ digits (Gibbs, 2002)

CH axillary nerve supplies subscapularis (Gibbs, 2002)

Af—femoral nerve innervates psoas minor (Gibbs, 2002)

Af—flexor digitorum longus innervated by muscular branches of tibial nerve (Gibbs, 2002)

CH—medial digit II innervated by superficial peroneal (Gibbs, 2002)

--Clusters of spindle cell pyramidal neurons--gorillas possess more than orangutans, chimps possess even more, and humans possess the greatest number (Uddin, 2004).

--tool usage (especially common in chimps: sticks for termites, wad of chewed leaves to remove water from tree holes, stout sticks to dig up ant, bee, or termite nests, leafy branches for sandals or gloves, leaf cushions to protect from thorny branches, bone picks to extract bone marrow, leaf napkins to clean themselves and infants, leaves to scoop water, natural objects to carry water, mortar and pestle to smash palm)

--learning of human sign language (chimps, gorillas, orangs)

--use of signs to communicate in wild (chimps)

--the ability to paint representationally (only shown after chimps could name their paintings)

--culture?—not all chimp populations have the same practices/tool usage, this is passed down in each population as a learned behavior


25.   Human Ancestor

Humans— increase in volume of limbic nuclei (Armstrong, 1980a)

Humans have 1 ½ times the number of neurons in the ventrolateral complex of the thalamus as great apes (Armstrong, 1980b)

Human brain about 3 times the size of that apes, expected of any which had our rate of growth after birth The rate of growth is similar (but slightly higer) to that in a chimp after birth but lasts considerably lonter. (Passingham, 1975). 

Neocortex 3.2 times bigger than chimp; cerebellum 2.8 (Passingham, 1975). 

In H. habilis, the cerebrum significantly increased in size in its frontal lobes and parietal lobes.  It grew taller but not longer (Tobias, 1987).

Pattern of gyri and sulci like humans and unlike apes (Tobias, 1987)..

Brocas and Wernickes areas enlarged (Tobias, 1987).

Meninges like modern (Tobias, 1987).

Development of inferior parietal lobule like humans and unlike apes (Tobias, 1987).

--main olfactory bulb greatly reduced in size

--damage to Broca’s area leads to loss of speech (in other primates voluntary sound production apparently unaffected)

--septum increase

--increase in cells in thalamic limbic system

--pulvinar nucleus largest thalamic nucleus