Retention of fish-like odontode overgrowth in Permian tetrapod dentition supports outside-in theory of tooth origins

Teeth are often thought of as structures that line the margins of the mouth; however, tooth-like structures called odontodes are commonly found on the dermal bones of many Palaeozoic vertebrates including early jawless fishes. ‘Odontode’ is a generalized term for all tooth-like dentine structures that have homologous tissues and development. This definition includes true teeth and the odontodes of early ‘fishes’, which have been recently examined to gain new insights into the still unresolved origin of teeth. Two leading hypotheses are frequently referenced in this debate: the ‘outside-in’ hypothesis, which posits that dermal odontodes evolutionarily migrate into the oral cavity, and the ‘inside-out’ hypothesis, which posits that teeth originated in the oropharyngeal cavity and then moved outwards into the oral cavity. Here, we show that, unlike the well-known one-to-one replacement patterns of marginal dentition, the palatal dentition of the early Permian tetrapods, including the dissorophoid amphibian Cacops and the early reptile Captorhinus , is overgrown by a new layer of bone to which the newest teeth are then attached. This same overgrowth pattern has been well documented in dermal and oral odontodes (i.e. teeth) of early fishes . We propose that this pattern represents the primitive condition for vertebrates and may even predate the origin of jaws. Therefore, this pattern crosses the fish–tetrapod transition, and the retention of this ancestral pattern in the palatal dentition of early terrestrial tetrapods provides strong support for the ‘outside-in’ hypothesis of tooth origins.

Hyperphalangy in a new sinemydid turtle from the Early Cretaceous Jehol Biota

Hyperphalangy is a rare condition in extant aquatic turtles, and mainly limited to soft-shelled turtles. Here we report a new freshwater turtle,Jeholochelys lingyuanensisgen. et sp. nov. from the Early Cretaceous Jehol Biota of western Liaoning, China. This new turtle is characterized by a hyperphalangy condition with one additional phalanx in pedal digit V, rather than the primitive condition (phalangeal formula: 2-3-3-3-3) of crown turtles.J. lingyuanensisis recovered with other coexisting turtles in the family Sinemydidae in the phylogenetic analysis. This discovery further confirms that hyperphalangy occurred multiple times in the early evolutionary history of the crown turtles. Hyperphalangy is possibly a homoplasy inJeholochelysand the soft-shelled turtles to adapt to the aquatic environments.

A morphological revision of Keraterpeton, the earliest horned nectridean from the Pennsylvanian of England and Ireland

ABSTRACTThe aquatic diplocaulid nectridean Keraterpeton galvani is the commonest taxon represented in the Jarrow Coal assemblage from Kilkenny, Ireland. The Jarrow locality has yielded the earliest known Carboniferous coal-swamp fauna in the fossil record and is, therefore, of importance in understanding the history and diversity of the diplocaulid clade. The morphology of Keraterpeton is described in detail with emphasis on newly observed anatomical features. A reconstruction of the palate includes the presence of interpterygoid vacuities and new morphological details of the pterygoid, parasphenoid and basicranial region. The hyoid apparatus comprising an ossified basibranchial element has not been reported previously in nectrideans. The structure of the scapulocoracoid and primitive nature of the humerus is described and the presence of a five-digit manus confirmed. Previously unrecognised accessory dermal ossifications are present in the pectoral girdle. Keraterpeton longtoni from the Bolsovian in Staffordshire, England, is also described and newly figured. The primitive condition in diplocaulids is defined on the basis of the earliest occurrence at Jarrow and discussed in relation to functional morphology and mode of life. The evolution of the diplocaulid clade is assessed in relation to the revised diagnoses that define the primitive condition in Keraterpeton.

Leaf and seedling morphology: the two prospective parameters to trace phylogeny in apiaceae subfamily apioideae.

Determination of phylogenetic affinity among the members of Apiaceae especially the subfamily Apioideae is much debatable. The morphological evidences on inflorescence, fruit and seed characters showed little concomitance with those derived from molecular parameters as far as groupings in clades are concerned. In the present study involving few selected Apiaceae members, a Dendrogram was computed and a putative evolutionary trend was outlined based on leaf margin insertion pattern and cotyledonary leaf features, general plant morphology as well as leaf surface micromorphology by SEM. The members of Apiaceae with broad-ovate pinnatifid to pinnatipartite leaves and ovate –lanceolate cotyledonary leaves were included in a distinct cluster but the members with pinnatisect – decompounds leaves and linear cotyledonary leaves were included in a separate cluster. Long Coriander (Eryngium foetidum) included in the subfamily Saniculoideae may represent the most primitive condition having simple entire leaf with spiny margin. The member like Long coriander might have served as progenitor stock from which Coriander, Celery, Parsley (all with ovate pinnatifid to pinnatipartite leaves) and Cumin, Fennel, Dill (all having pinnatisect to decompounds leaves with linear segments) might have originated as evidenced by gradual increase in marginal insertion. Similarly, gradual narrowing of ovate-lanceolate cotyledonary leaves might have given rise to narrow linear cotyledonary leaves. Leaf-margin insertion pattern and cotyledonary leaf features appeared to be promising in tracing phylogeny in Apiaceae especially in Apioideae. Simple entire leaf represents the primitive condition and evolution in Apiaceae supposed to have progressed towards gradual increase in marginal insertion leading to pinnately dissected, pinnatipartite and ultimately to decompound leaves with narrow linear segments. Dendrogram computed from morphological features showed concomitance with that phylogenetic trend as far as grouping and interrelationships of members are concerned. In the present study leaf margin insertion pattern and seedling morphology appeared to be instrumental in tracing the phylogeny in Apiaceae specially subfamily Apioideae while molecular systematics are not conclusive.

A Crassigyrinus-like jaw from the Tournaisian (Early Mississippian) of Scotland

ABSTRACTThe early tetrapod Crassigyrinus scoticus was a large aquatic predator from the mid Carboniferous (late Viséan or early Serpukovian) of Scotland, around 330 My in age. There are five main specimens with cranial remains: an articulated skeleton; two incomplete skulls; and two lower jaws. Crassigyrinus retains several apparently primitive features of the palatal dentition and lower jaw, and its phylogenetic position is disputed. A partial lower jaw resembling that of Crassigyrinus was discovered at Burnmouth in the Borders region of Scotland. The horizon in which it was found is dated as late Tournaisian, CM palynozone, around 350 My in age. Though it lacks dentition, the jaw preserves much of the postsplenial, angular and surangular, whose appearance externally and internally is almost identical to that of C. scoticus. Internally, the jaw shows a similarly limited extent of the suturing between the splenial series and the prearticular, a primitive condition. Externally, the type and distribution of dermal ornamentation closely matches that of C. scoticus, as does the deeply excavated and marginally positioned lateral line groove. As well as external and internal features, all specimens of C. scoticus are of similar skull size, though the Burnmouth jaw is somewhat smaller. If correctly attributable to Crassigyrinus, this specimen extends the existence of the genus by approximately 20 million years towards the base of the Carboniferous.

The Triadic Structure of the Human Psychism – between Psychopathology and Theology

The aim of this work is to present the triontic theory of the normal and pathological human psychism, elaborated by the Romanian psychiatrist Eduard Pamfil, and to highlight its deep connection with the Holy Trinity model of God. The main idea of the work is that mental illness, considered from a wider anthropo-phenomenological perspective, appears as the result of a deficit within interpersonal communication and, in a deeper way, of the lack of communion between human persons. According to Pamfil, the conscious human being is the result of the interaction of its three poles: I (ipseity), You (tui-ty) and He (ille-ity). Pamfil emphasises the inter-ontic nature of the person, its unity and uniqueness. I (ipseity), stands for the “archaic-primitive condition of the person”. You (tui-ty) stands for the “alter ego function”, the structural pole of personality. He (ille-ity) is the “systemic, axiological pole”. Thus, personality is a “mobile crossroad” between I, You and He, which are “moments of phenomenological subjectivity”. The psychopathological commentary of mental illness is made for three major clinical entities: neurosis, psychosis, psychopathy. The above presented theory is closely related to the Orthodox view of human person, who has its spiritual and moral model in the Holy Trinty of God. The modification of the triontic structure of the human person will lead to important changes in the existence of each person (I, You, He) within the trinitary relational system, among which mental illness is certainly the most significant.

Romundina and the evolutionary origin of teeth

Theories on the origin of vertebrate teeth have long focused on chondrichthyans as reflecting a primitive condition—but this is better informed by the extinct placoderms, which constitute a sister clade or grade to the living gnathostomes. Here, we show that ‘supragnathal’ toothplates from the acanthothoracid placoderm Romundina stellina comprise multi-cuspid teeth, each composed of an enameloid cap and core of dentine. These were added sequentially, approximately circumferentially, about a pioneer tooth. Teeth are bound to a bony plate that grew with the addition of marginal teeth. Homologous toothplates in arthrodire placoderms exhibit a more ordered arrangement of teeth that lack enameloid, but their organization into a gnathal, bound by layers of cellular bone associated with the addition of each successional tooth, is the same. The presence of enameloid in the teeth of Romundina suggests that it has been lost in other placoderms. Its covariation in the teeth and dermal skeleton of placoderms suggests a lack of independence early in the evolution of jawed vertebrates. It also appears that the dentition—manifest as discrete gnathal ossifications—was developmentally discrete from the jaws during this formative episode of vertebrate evolution.