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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