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Table 1 Summary of the systematic diagnosis of the fossil LACM 159892

From: The first known fossil Uma: ecological evolution and the origins of North American fringe-toed lizards

Positive Evidence

Morphological Feature

Hypothesis of character evolution

Alternative hypothesis

Reference

Teeth that are superficially attached to the jaw

Apomorphy of Lepidosauria

–

[54]

Pleurodont teeth

Apomorphy of Squamata

–

[55]

Fused postnatal premaxilla

Apomorphy of Squamata

–

[54, 56]

≥5 premaxillary tooth positions

Apomorphy of Pleurodonta within crown Iguania, independently acquired in Hydrosaurus and Japalura

–

[60, 61]

5–6 premaxillary tooth positions

Independently derived in Phrynosomatidae, Iguanidae, and Opluridae + Leiosauridae + Hoplocercidae

–

[15, 18]

Anterior premaxillary foramina (across Squamata)

Independently derived in Iguania, Anguimorpha, Cordylidae + Gerrhosauridae, Amphisbaenia

Independently derived in Iguania + Anguimorpha, Cordylidae + Gerrhosauridae, Amphisbaenia

[15, 18]

Anterior premaxillary foramina (within Phrynosomatidae)

Apomorphy of sand lizards within crown Phrynosomatidae, independently derived in Uta

Apomorphy of Phrynosomatidae, secondarily lost in Sceloporus, Urosaurus, and Petrosaurus

[15], this paper

Anterior face of the premaxilla and nasal process form a flat anterior face

Apomorphy of sand lizards within crown Phrynosomatidae

–

This paper

Rectangular body of premaxilla

Apomorphy of sand lizards within crown Phrynosomatidae

–

This paper

Posterodorsally directed nasal process

Apomorphy of sand lizards within crown Phrynosomatinae

–

This paper

Isoceles triangle-shaped nasal process

Independently acquired apomorphy of Uma and of Holbrookia

Apomorphy of sand lizards, lost in Callisaurus and Cophosaurus

This paper

Anterior foramen on the nasal process

Independently acquired apomorphy of Uma and of Callisaurus

Apomorphy of sand lizards, lost in Holbrookia and Cophosaurus

This paper

Relatively wide nasal process (dependent on shape of premaxilla)

Present only in Uma within sand lizard clade

–

[28]

Relatively square body of premaxilla

Apomorphy of Uma

–

This paper

Negative Evidence

 5–6 premaxillary tooth positions

≥7 premaxillary tooth positions is an apomorphy of Anguimorpha and of Cordylidae + Gerrhosauridae (see text for exceptions)

–

[9, 58]

 Posterodorsally directed nasal process

Apomorphy of sand lizards, absent in Amphisbaenia

–

[57]

 Anterior face of the premaxilla and nasal process form a flat anterior surface

Apomorphy of sand lizards, absent in Iguanidae, Hoplocercidae, Cordylidae + Gerrhosauridae

–

[15]

 Rectangular body of premaxilla

Apomorphy of sand lizards, absent in Opluridae + Leiosauridae

–

This paper

 Unicuspid teeth

The presence of multicuspid premaxillary teeth is an apomorphy of Iguanidae (see text for exceptions)

–

[63]

  1. The first section lists positive evidence for membership of the fossil in each clade, and the second section lists negative evidence for the inclusion of the fossil in a given clade. The reference column does not necessarily indicate that the character was considered an apomorphy by the author(s) who described the morphological feature